Solution Manual For Integrated Science 2026 Release By Bill W. Tillery, Eldon Enger and Frederick C.

Solution Manual For Integrated Science 2026 Release By Bill W. Tillery, Eldon Enger and Frederick C. Ross Chapters 1-26

Preface................................................................................................................. v 1. What is Science? ................................................................................................. 1 2. Motion ................................................................................................................. 11 3. Energy ................................................................................................................. 27 4. Heat and Temperature ......................................................................................... 41 5. Wave Motion and Sound .................................................................................... 53 6. Electricity ............................................................................................................ 61 7. Light .................................................................................................................... 73 8. Atoms and Periodic Properties............................................................................ 83 9. Chemical Reactions ............................................................................................ 93 10. Water and Solutions ............................................................................................101 11. Nuclear Reactions ...............................................................................................107 12. The Universe .......................................................................................................115 13. The Solar System ................................................................................................123 14. Earth in Space .....................................................................................................129 15. Earth ....................................................................................................................137 16. Earth‘s Surface ....................................................................................................145 17. Earth‘s Weather ..................................................................................................155 18. Earth‘s Waters .....................................................................................................163 19. Organic and Biochemistry...................................................................................169 20. The Nature of Living Things...............................................................................177 21. The Origin and Evolution of Life .......................................................................185 22. The History of Life on Earth ...............................................................................193 23. Ecology and Environment ...................................................................................201 24. Human Biology: Materials Exchange and Control .............................................209 25. Human Biology: Reproduction ...........................................................................217 26. Mendelian and Molecular Genetics ....................................................................225

Preface Integrated Science is designed for introductory-level, non-science majoring undergraduates and future teachers who are required to take one or two courses in the field of science. High school students will also benefit from this treatment. The goal of this textbook is to provide a conceptual overview of the different domains of science that are relevant to today‘s students. As such, there is an emphasis on conceptual understanding and less emphasis on doing rote calculations.

Similarly, there is an emphasis on applications for the modern world and far less emphasis on memorizing historical figures.

Many of the students taking this course are anxious about a science course, particularly if there are elements of mathematics. As such, it is the instructor‘s responsibility to use all available resources and energy to help students understand and appreciate the role science plays in our world. Today, society has a great need for a few technically trained people, but a much larger need for individuals who understand science. Thus, we need a text that presents a coherent and clear picture of all science disciplines—an interdisciplinary approach—which helps students confirm and calibrate the big picture with the real world.

Interdisciplinary science is an attempt to broaden and humanize science education by reducing and breaking down the barriers that enclose traditional science disciplines as distinct subjects. The spirit of interdisciplinary science is sometimes found in courses called ―General Science,‖ ―Combined Science,‖ or ―Integrated Science.‖ These courses draw concepts from a wide range of the traditional fields of science, but are not concentrated around certain problems or questions. For example, rather than just dealing with the physics of energy an interdisciplinary approach might consider broad aspects of energy—dealing with potential problems of an energy crisis—including social and ethical issues. There are a number of approaches that can be used in interdisciplinary science, including the teaching of science in a social, historical, philosophical, or problem-solving context but there is no single best approach. One of the characteristics of interdisciplinary science is that it is not constrained by the necessity of teaching certain facts or by traditions. It likewise cannot be imposed as a formal discipline, with certain facts to be learned. It is justified by its success in attracting and holding the attention and interest of students, making them a little wiser as they make their way toward various careers and callings.

This book is our attempt to help as instructors build their own mix of descriptive and analytical aspects of science, arousing student interest and feelings as they help students reach the educational goals of their particular course.

Integrated Science contains a number of innovative learning aids to help students, giving you more time to concentrate on presentations of important principles and concepts. A brief overview of some of these learning aids follows, together with suggestions about how they could be used.

The text contains a selection of multiple-choice, essay, or short-answer questions and two sets of quantitative exercises for each chapter. To meet a wide range of course objectives for different instructors, the questions are written at several taxonomic levels. They serve (1) as a source of feedback of student understandings, (2) as a means of preparing and studying for exams and quizzes, and (3) as a model for problem solving. The multiple-choice questions cover the main concepts, with answers provided for immediate correction or reinforcement of major understandings. The thought questions provide an excellent source of material for study group discussions. Many of these questions ask students to apply concepts, and the answers cannot be found specifically in the chapters. The Group A Exercises have complete solutions in appendix D of the text, with all unit work shown, and brief comments on needed understandings for successful working of problem exercises. Answers to these exercises are provided in this Instructor's Manual. Two sets are provided so that assignments can be made from the set without solutions (Group B). Diligent students who need help with the assigned problems are able to find a similar problem in the set with solutions (Group A) and study the model problemsolving technique.

There are enough multiple-choice, short-answer, and problem exercises spaced throughout the text that quiz and examination questions can be taken directly from the end-ofchapter materials. Nonscience students typically appreciate this kind of assistance in preparing for quizzes and examinations. The questions and problems selected from the text can be tailored to the abilities of a particular class. If this is done with forethought, the overall performance of a large nonscience class approaches a standard distribution. Additional multiple-choice questions with answers for each chapter are found in the accompanying and extensive test bank.

It is helpful if nonscience students are given an opportunity to familiarize themselves with the nature of a science course. They should know how it requires different reading, study, and thinking skills than required in other courses. Students cannot read a science text as they ―read‖ other textbooks (typically while thinking about something else). They must mentally ―act upon‖ the concepts, turning them over in their minds and making connections with previously learned concepts. For this reason, study groups of three or four students are suggested so students can question, talk about, ponder, and teach each other. Overall, the successful student will have a positive mental attitude; basic arithmetic skills, mostly dealing with fractions; an ability to follow directions; and an open mind and willingness to think.

Teaching Students Working in Collaborative Groups Collaborative group teaching techniques have been developed to correct many weaknesses of the traditional lecture-demonstration method, including overcoming the more obvious aspects of student passivity, memorizing equations, and a resulting fragmentation of knowledge. The idea of collaborative group teaching is simple and there are many easily implemented models that require just a few resources. In general, class members involved in

collaborative instruction are involved in structured learning situations, and they do receive some information from the instructor. The basic difference is that teams or groups of students work together until they successfully understand and complete an assignment. Such mutually worked assignments can range from answering a simple multiple-choice test item, to as complex as finding answers through unstructured research experiments in a laboratory setting.

No matter how complex the assignment, cooperative efforts result in individual group members gaining from each other's efforts, along with feelings of belonging to a group. Today, many nonscience students have a misconception that one does not have to attend lectures, but can learn by simply memorizing the textbook. And, to be fair, for too many college courses, this approach works. And, in the reverse as well, as far too many college faculty simply read students what is already in their textbook. As a result, to enhance students‘ understanding, it is impingent on the instructor to make class time worthwhile.

Cooperative group teaching involves more than directives for students to ―work together‖ or ―form teams.‖ As you have probably experienced, placing students in teams and telling them to work together does not in and of itself automatically result in cooperation. Not all groups are cooperative and invariably some ―team members‖ will want to sit by and watch others do all the work. To structure lessons so students do in fact work cooperatively with others requires an understanding of the basic things that can be done to make cooperation work. This will allow you to take existing lessons and restructure them for cooperative learning.

Peer instruction is one method of peer-to-peer teaching, advocated at Harvard University

by Physics Professor Eric Mazur. This teaching technique has been tried at several universities, and student testing shows that it works. It raises student scores on conceptual questions, as well as on traditional problem-solving questions. Peer instruction is described in Professor Mazur's book, Peer Instruction—A User's Manual (Prentice Hall, Inc, 1997). Professor Mazur's method includes a highly structured approach, and some of the ideas are briefly described here. There are basically three steps to the method: • The Peer Instruction sequence begins with an assignment to read certain materials in the text. The following class period begins with a one question (1 minute) quiz on that reading assignment. Students are expected to become familiar with definitions presented in the reading, and to begin thinking about the concepts. This is a test on the readings only, not on mastering the concepts.

• The reading quiz is followed by 15 minutes or so of demonstrations, videos, and clarification of concepts by the instructor.

• Students are then shown a conceptual multiple choice test question, perhaps on an overhead projector. These questions are designed to require students to make assumptions, make estimates, develop a model, or apply a worked out model. Students record their answers, then have ―one minute‖ to convince their classmates their answer is correct. The students then record a revised answer, which is reviewed by the professor (from students using a show of hands, posters, or one of numerous electronic systems) to learn what the students do or do not understand. The concept behind the correct answer is discussed. A new topic question is

selected if more than about 90% have the correct answer. A related question is selected next if about 30 to 80% have the correct answer. Less than 30% with the correct answer could mean the instructor should try again. His results have been replicated widely. He finds that this approach helps in the following ways: students were not passive, they were not memorizing equations, and they were learning from other students, as well as from the professor.

1

What is Science?

Contents Objects and Properties Quantifying Properties Measurement Systems Standard Units for the Metric System Length Mass Time Metric Prefixes Understandings from Measurements Data Ratios and Generalizations The Density Ratio Symbols and Equations The Nature of Science The Scientific Method Explanations and Investigations Scientific Laws Models and Theories Science, Nonscience, and Pseudoscience From Experimentation to Application Science and Nonscience Pseudoscience Limitations of Science

Overview Students begin by considering how one might observe and describe their immediate environment, and then logically proceed to an understanding that science is a particular strategy based observation-based logical reasoning and a way of describing their environment in a quantitative way. Within this opening chapter, deeper understandings about measurement as a way of describing the world. Concepts of ratios, proportions, and equations are developed as the student learns the specific scientific meaning of significant science words such as ―theory,‖ ―law,‖ and ―data.‖ A critical aspect is to point at the in the context of a science class, words like theory and

law have quite specific definitions that might differ in how these words are used in common, everyday language. The chapter develops a concept of the nature of scientific inquiry and presents science as a process. It distinguishes science from nonscientific approaches.

Suggestions 1. To begin the discussion ask the class their definition of science, accepting all answers as initially plausible. Ask students to give examples and counter examples. Consider the natural sciences as the study of matter and energy in living and nonliving systems, applied sciences (engineering), and social sciences in the discussion.

2. When discussing the meaning of concept, point out that different levels of thinking exist.

Lower levels are not necessarily incorrect but are incomplete compared to higher levels. For example, a young child considers a ―dog‖ to be the short brown furry animal that lives across the street. Later, the child learns that a dog can be any size (within limits) with highly variable colors, and in fact, dogs come in many sizes, colors, and patterns of colors. Still later, a dog (Canis familiaris) is understood to be a domestic mammal closely related to other animals (the common wolf). Each of these generalizations represents a concept, but at different levels of understanding. This discussion of levels of conceptualization will be useful later as a comparison when students argue a concept of something from a lower level of understanding.

Many nonscience students have an understanding of acceleration, for example, as a simple straight-line increase in velocity. This concept is not incorrect (the dog across the street), but it represents an incomplete level of conceptual understanding.

3. To introduce properties and referents, display an unusual rock (not pyrite) or object and ask the class to describe it as if talking to someone on the telephone. Keep track of the descriptive terms, then list them all together and ask the students if they could visualize the object if they heard this description over the telephone. The point about typical, vague everyday communications will be obvious. Ask for a volunteer who is majoring in education (or some other major requiring communications) and who loves coffee to describe the taste of coffee to someone who has never tasted it. The student will have difficulty because of the lack of a referent. The concept of a referent will probably be new to most nonscience students, but it is an important concept that will prove useful to them throughout the course. Another example is to show ½ the class an object and ask students to write a narrative description of how to ―draw‖ it; then, ask the other ½ to create a drawing from the written description (simultaneously, have the other ½ of class complete the task with a different object).

4. Many devices are available from scientific equipment companies to demonstrate the metric system of measurement, such as the plastic liter case. It is often useful to call attention to the similarities between the metric prefixes and the monetary system (deci- and dime, centi- and cent, and so forth). If students can make change, they can use the metric system.

5. In developing the concept of a ratio, it is useful to have a set of large blocks that you can actually measure to find the surface area to volume ratio. Show all calculations on an overhead transparency or chalkboard.

6. The development of the concepts of a proportionality statement, an equation, and the meaning and uses of symbols is critical if you plan to use a problem-solving approach. The three classes of equations provide an important mental framework on which future concepts will be hung. A student who does not ―understand‖ density has less of a problem learning that density is a ratio that describes a property of matter. Likewise, a student who does not ―understand‖ an electric field has less of a problem learning that an electric field is a concept that is defined by the relationships of an equation. Identifying equations throughout the course as ―property,‖ ―concept,‖ or ―relationship‖ equations will help students sort out their understandings in a meaningful way.

7. In the discussion of scientific laws, analysis of everyday ―laws‖ can be useful (as well as interesting and humorous). One statement of Murphy‘s law, for example, is that ―the bread always lands butter side down.‖ Ask the class what quantities are involved in this law and what the relationship is. Another everyday law is Bombeck‘s law: ―ugly rugs never wear out.‖ You could also make up a law — [your name]‘s law: ―the life span of a house plant is inversely proportional to its cost.‖ Analysis?

For Class Discussions 1. A large coffee cup initially half full of hot coffee is filled to the brim with ice cubes floating in the water, some floating above the water level. When the ice melts, the coffee will a. spill over the brim. b. stay at the same level. c. be less than before the ice melted.

2. A farmer wishes to fence in part of her field with a roll of wire fencing material. If all the roll of material is used in all situations, which shape of fenced-in space would enclose the greatest area? a. square b. rectangle c. both would have equal areas.

3. Again considering the farmer and a fence made with a roll of wire fencing material. If all the roll of material is used in all situations, which of the following shapes of fenced-in yard would now enclose the greatest area? a. right-angle triangle b. rectangle c. the answer will vary with the shape used.

4. Which of the following is usually measured by a ratio? a. The speed of a car. b. The density of a rock. c. Both speed and density are ratios. d. Nothing is measured with a ratio.

5. A 1 cm3 piece is removed from a very large lump of modeling clay with a volume of over 100,000 cm3. Which piece has the greatest density? a. The small piece. b. The large piece. c. Both the large and the small piece have the same density.

6. The nature of science is such that a. when proven, scientific theories become scientific laws. b. nature behaves as it does because of scientific laws. c. neither of these statements are true.

7. Which of the following statements is most correct? a. Science is always right. b. Nonscientific study has little value. c. Science has all the answers. d. Science seeks to explain natural occurrences.

8. When a scientist sees patterns or relationships among a number of isolated facts, a. laws or principles are developed. b. truth has been reached. c. elaborate tests must be developed to prove the pattern exists. d. as a rule, the pattern must be published.

9. Scientific method involves each of the following except a. systematic search for information. b. observation and experimentation. c. forming and testing possible solutions. d. formulation of laws and principles that control the observed facts.

10. Select the description of a controlled experiment: a. Group I, 50 mice fed, watered, Group II, 25 mice differently fed, watered. b. Group I, 25 mice fed, watered, Group II, 50 mice 1/2 fed, watered. c. Group A, 50 mice fed, watered, Group B, 50 mice fed differently, watered differently. d. Group A, 50 mice fed, watered, Group B, 50 mice fed different food, watered.

Answers: 1b (ice floats above the liquid coffee line because it is less dense; when the ice melts it occupies the same volume displaced while floating), 2a, 3c, 4c, 5c, 6c, 7d, 8a, 9d, 10d.

Answers to End of Chapter Concept Questions 1. A concept is a generalized mental image of an object or idea.

2. A measurement statement always contains a number and the name of the referent unit. The number tells ―how many,‖ and the unit explains ―of what.‖ 3. The primary advantage of the English system of measurement is that most United States citizens are familiar with the basic units and their sizes. The metric system has the advantage of easily converting the units to a convenient size merely by moving the decimal and using the appropriate prefix with the basic unit.

4. The meter is the metric standard of length and is defined as the distance light travels in a vacuum in 1/299,792,458 seconds. The metric standard of mass is the kilogram, which is defined as the mass of a standard kilogram kept by the International Bureau of Weights and Measures in France. The standard unit of time is the second, which is defined as the time required for a certain number of vibrations to occur in a type of cesium atom.

5. The density of a liquid does not depend upon the shape of its container. Density is a ratio of mass per unit volume. As long as this ratio stays the same the density does not change.

6. A flattened pancake of clay has the same density as a ball of the same clay. Even though the shape of the material has changed, the volume and the mass of the material have not changed.

Since density is a ratio of mass per unit volume the density is the same.

7. A hypothesis and a scientific theory are alike in that both are working explanations. A hypothesis, however, usually deals with a narrow range of phenomena, while a theory is a broad working hypothesis that forms the basis for thought and experimentation in a field of science.

8. A model is a mental or physical representation of something that cannot be directly observed.

A simpler representation of a complex phenomenon is also a model. A model is used as an easily visualized and understood analogy to some behavior or system that is not directly observable or is very complex.

9. Theories do not always enjoy complete acceptance but are rarely rejected completely. The better a theory explains the results of experiments and correctly predicts the results of new experiments, the greater the degree of acceptance. Theories that do not conform with experiments are usually modified and gain wider acceptance.

10. Pseudoscience is a methodology, presentation, or activity that appears to be or is presented as being scientific but is not supportable as valid or reliable. It can be identified by the following characteristics: a lack of valid substantiation of claims, untestable hypotheses, unwillingness to submit to rigorous testing, or inability to repeat the experiments.

11. Answering this question requires the critical thinking skills of clarifying values and developing criteria for evaluation. Answers will vary.

12. This question requires students to explore beliefs and evaluate arguments. Answers will vary.

13. This requires the student to evaluate a concept, comparing the concept with the real world.

The evaluation should note that density is a mass over volume ratio and larger and larger volumes with the same mass reduces the density.

14. Thinking precisely, the student will realize that doubling a quantity that is squared will result in a four-fold increase.

15. Thinking precisely and evaluating critical vocabulary is required. Answers will vary.

16. Thinking precisely and evaluating critical vocabulary is required. Answers will vary.

17. Exploring arguments and clarifying issues is required. Answers will vary.

End of Chapter Group B Solutions 1. Answers will vary. In general, mass and weight are proportional in a given location, so 1 kg  2.21 lb 1 =

1.00 kg 2.21 lb

mass 

1.00 kg 2.21 lb



 weight in pounds 

Kilograms can be converted to grams by the procedure described in the appendix A of the text.

1.00 kg = 1000.0 g 1 =

mgra ms

1000.0 g 1.00 kg

 mkil ograms 

1000.0 g 1.00 kg

2. Since density is given by the relationship  m/V, then

m V 39.5 g  5.0 cm3

 

39.5 5.0



 7.9

g cm3

g cm3

3. The volume of a sample of copper is given and the problem asks for the mass. From the relationship of  m/V, solving for the mass (m) tells you that the density () times the volume (V) gives you the mass, m = V. The density of copper, 8.96 g/cm3, is obtained from table 1.3 in the text, and m   V mV V  V m  V g     8.96 10.0 cm 3  3  cm   g  8.96  10.0  cm 3 3 cm  89.6 g

4. Solving the relationship  m/V for volume gives V = m/, and

V





5,000 g g 0.92 3 cm 5,000 g cm 3  0.92 1 g

 5, 400cm

3

The answer is rounded up to provide two significant figures, the least number given in the density of 0.92 g/cm3. This assumes that 5,000 grams of ice means exactly 5,000 grams, that is, that 5,000 has four significant figures.

5. A 50.0 cm3 sample with a mass of 51.5 grams has a density of m   V 51.5 g  50.0 cm 3 

51.5 50.0

 1.03

g cm 3 g cm3

According to table 1.3, 1.03 g/cm3 is the mass density of seawater, so the substance must be seawater.

6. The problem asks for a mass, gives the mass density of gasoline, and gives the volume.

Thus, you need the relationship between mass, volume, and mass density. The volume is given in liters (L), which should first be converted to cm3 because this is the unit in which density is expressed. The relationship of  m/V solved for mass is V, so the solution is m  m  V V g   m   0.680 94,600 cm 3  3  cm   g  0.680  94,600  cm 3 3 cm  64,300 g  

 64.3 kg

The answer is rounded up to provide three significant figures, the number of significant figures given in the density and volume measurements. The answer of 64,300 g is correct, but usually it is better to express the answer using ―standard‖ conventions being used. Using scientific notation would be better yet because of ease of showing significant figures and the ease of performing mathematical operations.

7. From table 1.3, the density of iron is given as 7.87 g/cm3. Converting 2.00 kg to the same units as the density gives 2,000 g. Solving  m/V for volume gives V

 



m  2,000 g g 7.87 cm 3 2,000 g cm 3  7.87 1 g

 254.13 cm 3  254 cm 3 8. The length of one side of the box is 1.00 m. Reasoning: Since the density of water is 1.00 g/cm3, then the volume of 1,000,000 g (1,000 kg) of water is 1,000,000 cm3. A cubic box with a volume of 1,000,000 cm3 is 100 cm (since 100  100  100 = 1,000,000). Converting 100 cm to m units, the cube is 1.00 m on each edge.

9. The relationship between mass, volume, and density is  m/V. The problem gives a volume, but not a mass. The mass, however, can be assumed to remain constant during the compression of the bun so the mass can be obtained from the original volume and density, or m    m  V V g   m   0.15 240 cm3 3  cm   g  0.15  240  cm3 3 cm  36 g





A mass of 36 g and the new volume of 195 cm3 mean that the new density of the crushed bread is m   V 36 g  195 cm 3 

36 195

 0.18

g cm 3 g cm 3

10. According to table 1.3, lead has a density of 11.4 g/cm3. Therefore a 1.00 cm3 sample of lead would have a mass of

 

m  m  V V g   m   11.4 1.00 cm 3  3  cm   g  11.4  1.00  cm 3 3 cm  11.4 g

Also according to table 1.3, iron has a density of 7.87 g/cm3. To balance a mass of 11.4 g of lead, a volume of this much iron would be required:

 

m  V V



V 



m  11.4 g g 7.87 cm3 11.4 g cm3  7.87 1 g

 1.45 cm3

2

Motion

Contents Describing Motion Measuring Motion Speed Velocity Acceleration Forces Horizontal Motion on Land Falling Objects

Compound Motion Vertical Projectiles Horizontal Projectiles Three Laws of Motion Newton‘s First Law of Motion Newton‘s Second Law of Motion Weight and Mass Newton‘s Third Law of Motion Momentum Conservation of Momentum Impulse Forces and Circular Motion Newton‘s Law of Gravitation Earth Satellites Weightlessness

Overview Describing an objects position and movement is a fundamental skill in science. This chapter focuses on describing the patterns of motion developed by Isaac Newton (A.D. 1642–1727).

Newton made many contributions to science and culture, but his three laws of motion and his law of gravitation are perhaps the most influential in the scientific domain. The three laws of motion are concerned with (1) what happens to the motion of a single object when no unbalanced forces are involved, (2) the relationship between the force, the mass of an object, and the resulting change of motion when an unbalanced force is involved, and (3) the relationship between the force experienced by two objects when they interact.

The laws of motion are universal, that is, they apply throughout the known universe and describe all motion. Throughout the universe mass is a measure of inertia, and inertia exists everywhere. A change of motion, acceleration, always results from an unbalanced force everywhere in the known universe. Finally, forces of the universe always come in pairs. Of the two forces one force is always equal in magnitude but opposite in direction to the other. The law of gravitation is also applicable throughout the known universe. All objects in the Solar System — the sun and the planets, the earth and its moon, and all orbiting satellites — obey the law of gravitation. To help students learn this core material, relativistic considerations should not be mentioned at this time; instead, concentrate on using Newton's laws of motion to describe how objects move, not Einstein's modifications of these laws at this time.

The key to understanding patterns of motion is to understand simultaneously the ideas represented in the three laws of motion. These areas follow: 1. Inertia is the resistance to a change in the state of motion of an object in the absence of an unbalanced force. An object at rest remains at rest and an object moving in a straight line retains its straight-line motion in the absence of an unbalanced force. The analysis of why a ball moving across a smooth floor comes to a stop, as presented in the previous chapter, is an important part of the development of this concept. Newton's first law of motion is also known as the law of inertia.

2. Mass is defined as a measure of inertia, that is, a resistance to a change in the state of motion of an object. Thus, the greater the mass the greater the resistance to a change in the state of motion. Acceleration is a change in the state of motion of an object. According to the definition developed in the previous chapter, an object that speeds up, slows down, or changes its direction of travel is undergoing an acceleration. Students who have difficulty accepting the meanings of mass and acceleration often have less difficulty if they are told these are definitions of the quantities. A force is a push or a pull that can cause a change in the state of motion of an object, that is, capable of producing an acceleration. The resulting acceleration is always in the same direction as the direction of the applied force. Newton's second law of motion is a relationship between mass, acceleration, and an unbalanced force that becomes clear when the conceptual meaning of these terms is understood. The relationship is that the greater the mass (inertia), the greater the force required to bring about a change in the state of motion (acceleration). In symbol form the relationship is a  F/m, or the more familiar F  ma. Since a newton of force is defined in terms of a certain mass (1 kg) and a certain acceleration (1 m/s2), the units are the same on both sides and the relationship becomes an equation, or F = ma. This is an example of an equation that defines a concept (see chapter 1).

3. A single force never occurs alone; a force is always produced by the interaction of two or more objects. There is always a matched and opposite force that occurs at the same time, and Newton's second law of motion is a statement of this relationship.

Suggestions 1. Students will benefit considerably from gaining repeated experiences watching objects move in various ways, and then finding ways to describe that motion completely. The need for precision and exact understanding should be emphasized as the various terms such as speed, velocity, rate, distance, acceleration, and others are presented. Stress the reasoning behind each equation, for example, that velocity is a ratio that describes a property of objects in motion.

Likewise, acceleration is a time rate of change of velocity, so (vf – vi)/t not only makes sense but can be reasoned out rather than memorized. Students are sometimes confused by the use of the symbol ―v‖ for both speed and velocity. Explain that speed is the same quantity as velocity but without direction, so the same symbol is used to simplify things. On the point of simplifying things, avoid the temptation to use calculus in any explanation or discussion. Moreover, starting with familiar unit systems such as mph is important so as not to cognitively overload students who are novices with metric systems.

2. Students are generally interested in ―relative to what‖ questions concerning motion. For example, what is the speed of an insect flying at 5 mph from the front to the back of a bus moving at 50 mph? What do you observe happening to an object dropped inside an airplane moving at 600 mph? What would an observer outside the airplane observe happening to the object?

3. The discussion of what happens to a ball rolling across the floor is an important one, and many students who think from an ―Aristotelian framework‖ are surprised by the analysis.

Research consistently shows that most students enter physics courses with such thinking and benefit from repeated interactions with phenomena to change their perspective. When discussing the role of friction and objects moving on the earth‘s surface, it is often interesting to ask why planets do not stop moving around the sun. Spur on the discussion by answering with another question, Why should they stop? It might be helpful to review the meaning of vector arrows that represent forces.

4. Another way to consider acceleration is to ask, How fast does ―how fast‖ change? If students have learned the concept of a ratio, they will understand the concept of uniform straight-line motion. The acceleration concepts, however, require the use of a ratio within another ratio, that is, a change of velocity (a ratio within) per unit of time (the acceleration ratio). This understanding is necessary (along with some basic math skills) to understand the meaning of such units as m/s2.

5. Demonstrations that illustrate the characteristics of projectile motion are illustrated in several devices found in scientific catalogs and using Internet-based demonstration videos. Among the most impressive is what is traditionally known as the ―monkey and hunter‖ demonstration where students are asked ―where should the paintball gun be pointed to hit a falling monkey who falls at the moment the paintball gun goes off?‖ Students often enjoy this demonstration along with the humor the instructor can induce while performing it.

6. There are many demonstrations and devices available from scientific suppliers that readily illustrate the laws of motion. However, none seems better than the personal experiences of students who have stood in the aisle of a bus as it starts moving, turns a corner, or comes to a stop. Use the three laws of motion to analyze the inertia, forces, and resulting changes of motion of a student standing in such an aisle of a bus. Modern video libraries often have amusement park roller coaster videos available online.

7. Stress that weight and mass are two entirely different concepts. Students struggle with this idea, and you will probably have to emphasize more than once that weight is another name for the gravitational force acting on an object, and that weight varies from place to place while mass does not. Use the second law of motion to show how weight can be used to calculate mass. A large demonstration spring scale calibrated in newtons can be used to show that a 1 kg mass weighs 9.8 N. Other masses can be weighed to show that weight and mass are proportional in a given location.

8. In solving problems involving the third law of motion, it is helpful for students to realize that a change in the state of motion always occurs in the same direction as the direction of an applied force. If you apply an unbalanced force on a ball toward the North, you might expect the ball to move toward the North. Thus, if one starts walking toward the North a force must have been applied in the same direction. The foot pushed on the ground in the opposite direction, so it must be that the equal and opposite force of the ground pushing on the foot is what caused the motion toward the North. It seems almost anthropomorphic to state that the ground pushed on a foot, but no other answer is possible with this analysis. The next step, so to is to realize that since the force of the foot on the ground equals the force of the ground on the foot (third law). Then the mass of the earth times the acceleration of the earth (second law) must equal the mass of the person times the acceleration of the person (ma = ma). This means at least two things: (1) that the earth must move when you walk across the surface (earth's acceleration must be greater than zero) and (2) that the earth would move with the same acceleration as the person if both had the same mass. Students are making progress when they can understand or make this kind of analysis.

9. A large coffee container attached to a strong cord and filled with water makes an interesting demonstration of centripetal force and inertia when whirled overhead. Practice this, however, before trying before a class.

10. Students benefit from being asked to make predictions BEFORE they see a demonstration enacted. Some common demonstrations available to illustrate these ideas include: (a) Show the stroboscopic effect as a means of measuring motion. Use a strobe light or hand stroboscopes, for example, to ―stop‖ the motion of a spinning wheel of an upside-down bicycle.

(b) Roll a steel ball down a long ramp and mark the distance at the end of each second. Plot distance vs. time and distance vs. time squared to verify the acceleration equation. (c) Crumple a sheet of paper tightly into a small ball. Drop the crumpled ball and a sheet of uncrumpled paper from the same height. Discuss which is accelerated at 9.8 m/s2 and the roll of air resistance. (d) Use the commercial apparatus that shoots or moves one ball horizontally and drops another ball vertically at the same time. A single ―click‖ means that both balls hit the floor at the same time. This illustrates the independence of velocities. (e) Drop a small steel ball from the highest place practical into a tub of water. Make sure this is done on a day without wind and with no person near the tub. Time the fall with a stopwatch.

Measure the vertical distance accurately, then find g from d = 1/2gt2. (f) Use a spring scale to show that a 1.0 kg mass weighs 9.8 N. Use other masses to show that the weight of an object is always proportional to the mass in a given location. (g) Use an air track to illustrate Newton‘s first and second law of motion. If an air track is not available, consider a slab of ice or dry ice on a smooth demonstration tabletop. Wood blocks can be set on the ice to add mass. (h) Will a jet plane backed up to a brick wall take off faster than one out in the open? Compare the jet plane to a balloon filled with air, that is, the balloon is propelled by a jet of escaping air.

Thus the movement is a consequence of Newton‘s third law and the brick wall will make no difference–a jet plane backed up to a brick will take off the same as an identical jet plane out in the open. (i) Seat yourself on a small cart with a CO2 fire extinguisher or a bottle of compressed air from the shop. Hold the device between your feet and legs with the escape valve pointed away from your body. With the way clear behind you, carefully discharge a short burst of gas as you accelerate. This attention-grabber affords an opportunity to review all three of Newton‘s Laws of motion. (j) Demonstrate that the acceleration of a freely falling object is independent of weight. Use a commercial ―free-fall tube‖ if one is available. If not, try a large-diameter 1 m glass or plastic tube with a solid stopper in one end and a one-hole stopper in the other. Place a coil and a feather in the tube, then connect the one-hole stopper to a vacuum pump. Invert the tube to show how the coin and feather fall in air. Pump air from the tube, then again invert to show the coin and feather in free fall.

For Class Discussions 1. Neglecting air resistance, a ball dropped from a 3rd floor window will have a. constant speed and constant acceleration. b. increasing speed and increasing acceleration. c. increasing speed and decreasing acceleration. d. increasing speed and constant acceleration.

2. Neglecting air resistance, a car sliding down the icy slope of a steep hill will have a. constant speed and constant acceleration. b. increasing speed and increasing acceleration. c. increasing speed and decreasing acceleration. d. increasing speed and constant acceleration.

3. Neglecting air resistance, a ball thrown straight up will come to a momentary stop at the top of the path. What is the acceleration of the ball during this stop? a. 9.8 m/s2. b. zero. c. less than 9.8 m/s2. d. more than 9.8 m/s2.

4. Neglecting air resistance, the ball thrown straight up comes to a momentary stop at the top of the path, then falls for 1.0 s. What is speed of the ball after falling 1.0 s? a. 1 m/s b. 4.9 m/s c. 9.8 m/s d. 19.6 m/s 5. Neglecting air resistance, the ball thrown straight up comes to a momentary stop at the top of the path, then falls for 2.0 s. What distance did the ball fall during the 2.0 s? a. 1 m b. 4.9 m c. 9.8 m d. 19.6 m 6. A ball is thrown straight up at the same time an ball is thrown straight down from a bridge, with the same initial speed. Neglecting air resistance, which ball would have a greater speed when it hits the ground? a. The one thrown straight up. b. The one thrown straight down. c. Both balls would have the same speed.

7. After being released, a ball thrown straight down from a bridge would have an acceleration of a. 9.8 m/s2. b. zero. c. less than 9.8 m/s2. d. more than 9.8 m/s2.

8. A gun is aimed at an apple hanging from a tree. The instant the gun is fired the apple falls to the ground, and the bullet a. hits the apple. b. arrives late, missing the apple. c. may or may not hit the apple, depending on how fast it is moving.

9. You are at rest with a grocery cart at the supermarket, when you apply a certain force to the cart for a short time and acquire a certain speed. Suppose you had bought more groceries, enough to double the mass of the groceries and cart. Neglecting friction, doubling the mass would have what effect on the resulting final speed if you used the same force for the same length of time? The new final speed would be a. one-fourth. b. one-half. c. the same time. d. doubled. e. quadrupled.

10. You are moving a grocery cart at a constant speed in a straight line down the aisle of a store.

The forces on the cart are a. unbalanced, in the direction of the movement. b. balanced, with a net force of zero. c. equal to the force of gravity acting on the cart. d. greater than the frictional forces opposing the motion of the cart.

11. Considering the gravitational attraction between the Earth and Moon, the a. more massive Earth pulls harder on the less massive Moon. b. less massive Moon pulls harder on the more massive Earth. c. attraction between the Earth and Moon and the Moon and Earth are equal. d. attraction varies with the Moon phase, being greatest at a full moon.

12. You are outside a store, moving a loaded grocery cart down the street on a very steep hill. It is difficult, but you are able to pull back on the handle and keep the cart moving down the street in a straight line and at a constant speed. The forces on the cart are a. unbalanced, in the direction of the movement. b. balanced, with a net force of zero. c. unbalanced if there is a massive load of groceries. d. equal to the force of gravity acting on the cart. e. greater than the frictional forces opposing the motion of the cart.

13. Which of the following must be true about a horse pulling a buggy? a. According to the third law of motion, the horse pulls on the buggy and the buggy pulls on the horse with an equal and opposite force. Therefore, the net force is zero and the buggy cannot move. b. Since they move forward, this means the horse is pulling harder on the buggy than the buggy is pulling on the horse. c. The action force from the horse is quicker than the reaction force from the buggy, so the buggy moves forward. d. The action-reaction force between the horse and buggy are equal, but the resisting frictional force on the buggy is smaller since it is on wheels.

14. Suppose you have a choice of driving your speeding car head on into a massive concrete wall or hitting an identical car head on. Which would produce the greatest change in the momentum of your car? a. The identical car. b. The concrete wall. c. Both would be equal.

15. A small, compact car and a large sports utility vehicle collide head on and stick together.

Which vehicle had the larger momentum change? a. The small, compact car. b. The large sports utility vehicle. c. Both would be equal.

16. Again consider the small, compact car and large sports utility vehicle that collided head on and stuck together. Which experienced the larger deceleration during the collision? a. The small, compact car. b. The large sports utility vehicle. c. Both would be equal.

Answers: 1d, 2c (a = g straight down, but decreases to zero on a level surface), 3a (acceleration is a rate of change of velocity and gravity is acting, F = ma, so a must be occurring), 4b (initial speed was zero, average speed is one-half of final speed), 5d, 6c, 7a (after release only gravity acts on ball), 8a (the apple and bullet accelerate downward together, no matter how fast the bullet is moving), 9b, 10b, 11c, 12b, 13d, 14c, 15c, 16a.

Answers to End of Chapter Concept Questions 1. The speed of the insect relative to the ground is the 50.0 mi/h of the bus plus the 5.0 mi/h of the insect relative to the bus for a total of 55 mi/h. Relative to the bus alone the speed of the insect is 5.0 mi/h.

2. After it leaves the rifle barrel, the force of gravity acting straight down is the only force acting on the bullet.

3. Gravity does not depend upon some medium to convey its ―force at a distance,‖ so it can operate in a vacuum.

4. Yes, the small car would have to be moving with a much higher velocity, but it can have the same momentum since momentum is mass times velocity.

5. A net force of zero is required to maintain a constant velocity. The force of friction is balanced out by the force from the engine as a car drives with a constant velocity.

6. The action and reaction forces are between two objects that are interacting. An unbalanced force occurs on a single object as the result of one or more interactions with other objects.

7. The change of momentum from hitting the ground, or impulse, is the product of the applied force and time that the force is applied. The product of the force and the time is always the same, but both can be varied. Bending your knees has you hit the ground increases the time, therefore reducing the applied force.

8. Your weight can change from place to place because weight is a downward force from gravitational attraction on your mass and the force of gravity can vary from place to place.

9. Nothing! There is no force parallel to the motion to increase or decrease the earth's speed, so the speed remains constant.

10. If you have something to throw, such as car keys or a snowball, you can easily get off the frictionless ice. Since the force you apply to the thrown object results in an equal and opposite force (the third law of motion), you will move in the opposite direction as the object is thrown (the second law of motion). The same result can be achieved by blowing a puff of air in a direction opposite to the way you wish to move.

11. Considering everything else to be equal, the two rockets will have the same acceleration. In both cases, the acceleration results as burning rocket fuel escapes the rocket, exerting an unbalanced force on the rocket (third law) and the rocket accelerates during the applied force (second law). The acceleration has nothing to do with the escaping gases having something to ―push against.‖ 12. The astronaut is traveling with the same speed as the spaceship as he or she leaves. If no net force is applied parallel to the direction of motion of either the astronaut or the spaceship, they will both maintain a constant velocity and will stay together.

13. Similar – both speed and velocity describe a magnitude of motion, that is, how fast something is moving. Differences – velocity must specify a direction; speed does not.

14. Similar – both velocity and acceleration describe motion. Differences – velocity specifies how fast something is moving in a particular direction; acceleration specified a change of velocity (speed, direction, or both).

15. This requires a comparison of beliefs and an analysis and comparison with new contexts.

Answers will vary, but should show understanding of Newton‘s three laws of motion.

16. This question requires both clarifying beliefs and comparing perspectives. Answers will vary.

17. Requires refining of understanding. Mass is a measure of inertia, meaning a resistance to a change of motion. Weight is gravitational acceleration acting on a mass. Since gravity can vary from place to place, the weight as a result of gravity will also vary from place to place.

18. Requires clarifying and analyzing several conceptual understandings. Newton‘s first law of motion tells us that motion is unchanged in a straight line without an unbalanced force. An object moving on the end of a string in a circular path is pulled out of a straight line by a centripetal force on the string. The object will move off in a straight line if the string breaks. It would move off in some other direction if other forces were involved.

End of Chapter Group B Solutions 1.

The distance that a sound with this velocity travels in the given time is v 

d  d  vt t   343 m / s  0.500 s   172 m

172 m 2  86.0 m Since the sound traveled from the rifle to the cliff and then back, the cliff must be 172 m/2 = 86.0 m away.

2.

vf  vi t 15 m / s  5.0 m / s  6.0 s

a

10.0 m 1  6.0 s s m  1.7 2 s 

3. v

 

d t 400.0 km 4.5 h

 88.8888 km/h  89 km/h (2 significant figures)

4.

F = ma 

 6,000 kg    2.2 2 

 6,000  2.2

 kg  m s2

m s 

 1.3  104 N  1  104 N (1 significant figure)

5.

The mass of a 39,200 N space probe on the surface of Earth is w w  mg  m  g kg  m 39, 200 2 s  m 9.8 2 s  4,000 kg  4.0  103 kg (2 significant figures) The probe will have the same mass on Mars.

6.

w  mg m  (60.0 kg)(9.8 2 ) s kg  m  588 s2  590 N

7.

p  mv m    30.0 kg   500  s   kg  m  15,000 s kg  m  20,000 (one significant figure) s

8.

Mass of ball: F  ma  m 

F a

kg  m s2  m 9.8 2 s 39.2 kg  m s2   9.8 s2 m  4.0 kg 39.2

Momentum of ball:

p  mv m    4.0 kg   7.00  s  kg  m  28 s

9.

Listing the known and unknown quantities: Shell m = 30.0 kg Shell v = 500 m/s

Cannon m = 2,000 kg Cannon v = ? m/s

This is a conservation of momentum question, where the shell and cannon can be considered as a system of interacting objects: Shell momentum = -Cannon momentum

 mv s = -  mv c  mv s -  mv c = 0  30.0 kg   500 

m    2,000 kg  vc  0 s

m   15,000 kg     2,000 kg  vc   0 s  m   15,000 kg     2,000 kg  vc  s  m 15,000 kg  s vc  2,000 kg 15,000 kg 1 m   2,000 1 kg s m  7.5 s m  8 (1 significant figure) s The cannon recoils with a velocity of 8 m/s. 

10.

(a) F

 ma  m 

m 

F a

and

Ft vf  vi

a



vf  vi t

 3,000.0 N    5.00 s 



 km m 1 hr   36.0 hr  1000 km  3,000 s    0    kg  m    3,000.0 2    5.00 s  s    m 10.0 s 3,000.0  5.00 kg  m s s    10.0 s2 1 m 3  1.50  10 kg

(b)

w = mg 

1.50  10 kg    9.8 sm 



1.50  10    9.8 kg1  sm

3

2

3

 1.5  104 N

2

11.

F 

mv 2 r

m 1.00 kg   5.00  s    0.500 m

2

 m2  1.00 kg 25.0    s2    0.500 m 1.00  25.0 kg m 2 1   0.500 1 s2 m kg  m  50.0 s2  50.0 N 

12.

vf  vi  t v  vi v  vi F m  f  tm f t F F  ma and

a

m   0  2.00  s  200.0 kg   100.0 N 

 200.0kg  2.00 

 4.00 s

2.00

kg m s2   1 s kg  m

3

Energy

Contents Work Units of Work Power Motion, Position, and Energy Potential Energy Kinetic Energy Energy Flow Energy Forms Energy Conversion Energy Conservation Energy Transfer Energy Sources Today Petroleum Coal Moving Water Nuclear Conserving Energy Energy Tomorrow Solar Technologies Geothermal Energy Hydrogen

Overview Energy and work are generally difficult concepts for many nonscience students for several reasons. First, energy is a common word in everyday language that has a broader meaning that it has in the domain of physics. The second reason students find energy difficult is because they often consider it to be a substance that evaporates, rather than changes form. This chapter begins with the more easily visualized concepts of work and power, develops two general aspects of energy (position and motion) based on concepts learned in previous chapters, and then uses these aspects as a basis for a conceptual scheme for understanding energy. This scheme is then applied in considering the energy sources used today.

Students will benefit from learning that work and energy are closely related concepts.

Work is defined in this chapter by using the second class of equations (defining a concept; see chapter 1). Work is defined as the product of a force moving through a distance, or W = Fd. Both metric units and English units are presented because both are in everyday use today. The metric unit of work is the newton-meter, which is called a joule. The English unit of work is the foot-pound, which does not have another name. Along with learning the scientific meaning of work, students will need to become accustomed to using the terms in the sense of work accomplished or the potential for doing work, for example, ―How much work was done on . . .?‖ and ―How much work can the object now do?‖ The energy of position, or potential energy, can be measured by how much work is done on an object to give it energy of position or by how much work it can now do because of its position. Since work involves forces and movement through a distance, the variables involved are the force, the movement (acceleration = change of motion), and the mass of the object (a measure of inertia, or resistance to a change of motion). Thus, a non-calculus calculation of potential energy can begin with Newton's second law of motion, or F = ma. To obtain an expression of work, both sides of this equation are multiplied by distance, h (for height, which is a vertical distance), which gives Fd = mah. For gravitational potential energy, the acceleration is g and the relationship is W = mgh or PE = mgh. The potential energy unit turns out to be joules, which is the same unit used to do work to create the potential energy to begin with. Thus, from this analysis comes the first idea that work = energy = work, or that both are fundamentally the same thing.

The energy of motion, or kinetic energy, can also be measured by how much work is done on an object to give it energy of motion or by how much work it can now do because of its motion. Again, work involves forces and movement through a distance such as are involved in throwing a baseball. The non-calculus relationship again involves the variables in Newton's second law of motion, F = ma. As before, both sides are multiplied by distance to obtain an expression of work, which in this case is the energy of motion, and KE = mad. Now we need to put the distance quantity (d) in terms of a final velocity (vf) for kinetic energy. This requires the use of the first three equations presented in chapter 2: Step 1. The relationship between the average velocity, distance, and time is v 

d t

 d  vt

Step 2. The average velocity quantity and the time quantity could now be substituted for d in KE = mad, but they are still not in terms of a final velocity. First, a final velocity is substituted for average velocity ( v )

v 

vi  vf 2

 vf 

v 2

 where vi  0 

Step 3. Next a final velocity is substituted for time by rearranging the equation for acceleration a 

vf  vi t

 t 

vf a

 where vi  0 

Now it is a matter of simple substitution of the solutions in step 2 and step 3 into the rearrangement shown in step 1, or d  vt

(from step 1)

vf t (from step 2) 2  v  v  d   f   f  (from step 3)  2  a  d

These terms can now be substituted for the d in KE = mad to put the equation in terms of velocity rather than distance, and

 v  v  KE  ma  f   f   2  a  The a's now cancel and the equation is rearranged to the more familiar expression of kinetic energy, which is KE 

1 2 mv 2

The kinetic energy unit turns out to be a joule, which is the same unit used to do the work to create the kinetic energy to begin with. Again, you can see that work = energy = work, that is, both energy and work are fundamentally the same thing.

The similarities between energy and work are discussed throughout the presentation of the energy flow scheme. Note that many textbooks define heat as a form of energy rather than energy in transit between two forms. Either definition is correct. Considering heat as a form of energy, however, is a conceptual level akin to considering a dog as the animal that lives across the street (see chapter 1 in this manual).

Suggestions

1. An important key to understanding the concepts presented in this chapter is understanding the relationship between the work performed to give an object potential or kinetic energy, the energy that the object has by way of its position or motion, and the work that an object can do as a result of its kinetic or potential energy. Students will benefit from seeing and analyzing many examples that have both conceptual and numerical components. Use a demonstration spring scale calibrated in newtons to lift a kilogram mass one meter from the floor to a shelf. Demonstrate the weight of the mass is 9.8 N, and the work done is 9.8 J in lifting the mass 1 m. Discuss that the work is done against gravity. Now use the equation to show the potential energy of the mass is now 9.8 J as a result of the work done on it. Compare the work done on the mass, the potential energy that the mass has as a result, and the work the mass can now do as a result of its position in the attractive force of earth's gravitational field.

2. Students often find it interesting to compare the power ratings in one system of measurement with power ratings in the other. A 1500 W hair dryer, for example, has an English power equivalent of almost 2 hp. A 100 hp car, on the other hand, has a metric power rating of a little less than 75 kW, especially as it relates to their end of month electricity power bill.

3. The expressions of kinetic energy, potential energy, and the law of conservation of energy apply to the conversion of any energy form to another. If the students seem confused by electromagnetic or nuclear interactions, concentrate on mechanical interactions. They can learn the relationships involved in the mechanical interactions and apply the concepts to more abstract materials in later chapters.

4. A swinging pendulum provides a good demonstration of the conversion of potential to kinetic energy and from kinetic to potential energy. A meter stick can be used to show that the bob rises to about the same height as it speeds up, as it descends, then slows as it moves up the other half of the arc of its swing. Conservation laws can also be shown by the popular line of steel balls supported by wires on a frame. When one ball is released to hit the line of balls, it stops while one swings out the other side. If two are allowed to hit the line of balls, they stop while two swing out the other side. These elastic collisions demonstrate both the law of conservation of energy and the law of conservation of momentum.

5. Bartlett, A. A. (1978). Forgotten fundamentals of the energy crisis. American Journal of Physics, 46(9), 876-888 provides an interesting resource on exponential growth and doubling time as applied to our energy sources that still applies today.

6. Additional demonstrations: (a) Use a pendulum to demonstrate conservation of energy as the bob converts potential energy (top of its swing) to kinetic energy (bottom of swing), then back to potential again. Point out that a book falling from a shelf also converts PE (top of fall) to KE (bottom of fall). (b) Support a long piece of transparent tubing in a long arc, then roll marbles down one side to see if they roll to the same height at the other side of the tube. Add a loop or several loops and analyze potential energy and kinetic energy at the beginning and end of each loop compared to the overall length of tubing.

(c) A line of steel spheres supported by strings can be used to demonstrate conservation of energy in elastic collisions. One mass pulled back and released will result in one mass leaving the row at the other end. If two are pulled back and released, two will leave the other end and so on. Try pulling one mass back from one side and two back from the other side, releasing all at the same time. (d) If your classroom is above or below street level, you can ask each student to calculate how much work is done bringing books to (or from) class.

For Class Discussions 1. A spring-loaded paper clamp exerts a force of 2 N on 10 sheets of paper it is holding together.

Is the clamp doing work as it holds the papers together? a. Yes b. No 2. An iron cannon ball and a lightweight basketball were dropped at the same time from the top of a building. At the instant before the balls hit the sidewalk, the heavier cannon ball has greater a. velocity. b. acceleration. c. kinetic energy. d. weight.

3. Two students are poised to dive off equal height diving towers to a swimming pool below.

Student B is twice as massive as student A. Which of the following is true? a. Student B will reach the water sooner than student A. b. Both students have the same gravitational potential energy. c. Both students will have the same kinetic energy just before hitting the water. d. Student B did twice as much work climbing the tower.

4. The two students are again poised to dive off equal height diving towers to a swimming pool below. Student B is twice as massive as student A. Just before hitting the water, student B will have a. the same kinetic energy as student A. b. twice as much kinetic energy as student A. c. half as much kinetic energy as student A. d. four times as much kinetic energy as student A.

5. A car is moving straight down a highway under ideal conditions. What factor has the greatest influence on how much work must be done on the car to bring it to a complete stop? a. How fast it is moving. b. The weight of the car. c. The mass of the car. d. The latitude of the location.

6. Two identical cars are moving straight down a highway under identical conditions, except car B is moving three as fast as car A. How much more work is needed to stop car B? a. Twice as much. b. Three times as much. c. Six times as much. d. Nine times as much.

7. Two identical cars start at rest on a long hill, with car B twice as high as car A. How much more work is needed to stop car B at the bottom of the hill? a. Twice as much. b. Three times as much. c. Six times as much. d. Nine times as much.

8. Suppose your grocery cart is moving at a constant momentum in a straight line down the aisle of a store, without friction. How will the speed change as you drop groceries into the moving cart? a. increase b. decrease c. remain the same 9. Again consider your grocery cart that is moving at a constant momentum in a straight line down the aisle of a store, without friction. How will the kinetic energy of the cart change as you drop groceries into it? a. increase b. decrease c. remain the same

10. A water balloon dropped from a dorm window does not break on the sidewalk. From how much higher would you need to drop the balloon to double the speed of impact? a. Twice as high. b. Three times as high. c. Four times as high. d. Eight times as high.

Answers: 1b, 2c, 3d, 4b, 5a, 6d (W = KE = 1/2mv2 and 32 = 9), 7a (2mgh = 21/2mv2 = 2W), 8b (constant p with increased m in p = mv), 9b, 10c (v = 2gh).

Answers to End of Chapter Concept Questions 1. Energy is the ability to do work and doing work on something gives it energy.

2. The work done is equal to the increase in gravitational potential energy.

3. Relative to the bus, the person has no kinetic energy because the person is at rest relative to the bus. Relative to the ground, however, the person does have kinetic energy because the person is moving with the same speed as the bus.

4. Because a time factor is in the rating: a watt is a unit of power, and power is work per unit time. A 100 W light bulb uses energy at a rate of 100 J per s.

5. A kWh is a unit of work, and since energy is the ability to do work, it is also a unit of energy.

In terms of units, a watt is a joule per second, and an hour, as a second, is a unit of time. The time units cancel, leaving a unit of a joule, which can be used to measure either work or energy.

6. Energy is eventually converted into unrecoverable radiant energy, so new sources of convertible energy must be found in order to continue performing useful work.

7. If the spring clamp does not cause the paper to move, it is not acting through a distance and no work is done.

8. Fossil fuels contain energy from plants or animals that lived millions of years ago. These plants and animals are known from the fossils they left behind, and the energy in the fuels represents energy stored from these ancient organisms.

9. The machine would not be in accord with the principle of conservation of energy.

10. A joule is one newton-meter. A joule of work is from a force acting through a distance while a joule of energy is the ability to perform one joule of work. The use of the same unit means that work and energy are fundamentally the same thing.

11. The energy required is less on the moon because the weight of the object (the downward force due to gravity) depends upon the force of gravity, which is less on the moon than on the earth. Less energy is needed to do the work of raising the mass on the moon, and the elevated object on the moon has less potential energy as a consequence of the work done.

12. The energy is converted to heat and sound.

13. Analyzing and evaluating the definition of mechanical work shows that work is defined as the product of a force and the distance moved as a result of the force. In other words, movement is part of the definition of work.

14. Similarities – both involve a force moving something through a distance. Difference – power is a time rate of doing work; work by itself does not involve time.

15. This requires analyzing and evaluating an interpretation of work. The correct analysis is that this is a true statement.

16. This requires analyzing, exploring beliefs, and clarifying a conceptual understanding.

Answers will vary, but should clarify that work input always equals work output.

17. Reasoning precisely about the equation shows that K.E. varies directly with the mass, but varies with the square of the velocity. Thus, twice the mass requires twice the work (K.E.) to bring a car to a stop, but twice the speed requires four times the work to bring the car to a stop.

18. Generating and analyzing this situation will result in answers that vary.

19. Analysis should show mechanical energy (gravitational), chemical (electromagnetic), radiant (electromagnetic), electrical (electromagnetic), and nuclear (nuclear).

20. Evaluating and analyzing should show that this device does not exist.

21. Evaluating and analyzing should show that such contradictions do not exist.

End of Chapter Group B Solutions 1.

W d 1, 200 J  1.5m

W  Fd  F 

1, 200 1.5  800 N 

 N  m  

 8.0  102 N

2.

W  Fd   980.0 N  0.015 m   14.7 N  m  15 J

1  m

3.

W  Fd  mgd m    5.0 kg   9.8 2   0.300 m  s   kg  m  5.0  9.8  0.300 m s2  14.7 N  m  15 J

4.

PE  mgh  h 

KE mg

kg  m m s2  m  250 kg   9.8 2  s   196, 000 kg  m 1 s 2    2, 450 s2 kg m  80. m 196,000

5.

P



mgh t

1,500.0 kg   9.8 2   360.0 m  m s   60.0 s

 kg  m  m 1,500.0  9.8  360.0   s2    s  60.0  5, 292,000 N  m 60.0 s J  88, 200 s  88, 200 W 

1.00 hp  88, 200 W 746 W 88, 200 hp  W 746 W 118 hp 120 hp (two significant figures)

6.

KE 

1 2 mv 2

1 m    0.0300 kg   200.0  2 s  

2

 1 m2   0.0300 kg   40,000.0 2  2 s  

1 m2  0.0300  40,000.0  kg  2 2 s kg  m  600 2  m s  6.00  102 Nm 

 6.00  102 J

7. The work done on an object to put it in motion or the work done by a moving object as a result of its motion is equal to its kinetic energy, so

KE 

1 2 mv 2

1 m    0.0300 kg   200  2 s   

2

 1 m2   0.0300kg   40, 000 2  2 s  

1 m2  0.0300  40, 000  kg  2 2 s kg  m  600 2  m s  600 J 

 6.00 102 J

8. (a)

W  Fd  mgh m   10.0 kg   9.8 2  15 m  s   kg  m  10.0  9.8 15 m s2  1, 470 J  1,500 J (2 significant figures)

(b)

PE  mgh m   10.0 kg   9.8 2  15 m  s   kg  m  10.0  9.8  15 m s2  1,470 J  1,500 (2 significant figures)

9.

(a) W  Fd   50.0 lb 10.0 ft   50.0  10.0 lb  ft  500 ft  lb  5.00  10 2 ft  lb

(b)

PE  mgh h  0, so PE  0

10.

(a)

W  Fd  mgh m    50.0 kg   9.8 2  1.5 m  s   kg  m  50.0  9.8  1.5 m s2  735 N  m  740 J

(b)

PE  mgh m   100 kg   9.8 2  15m  s   kg  m  50.0  9.8  1.5 m s2  735 N  m  740 J

(c) Since the PE lost is equal to the KE gained, then KE = 740 J.

11.

KE  

1 2 mv 2 1 m 800.0 kg   20.0  2 s 

2

 1 m2    800.0 kg   400 2  2 s   1 m2 800.0  400  kg  2 2 s kg  m  160,000 2  m s  160,000 Nm 

 1.60  105 J

KE 

1 2 mv 2 2



1 m 800.0 kg   40.0  2 s 



 1 m2  800.0 kg 1,600    2 s2  

1 m2 800.0 1,600  kg  2 2 s kg  m  640,000 2  m s  640,000 Nm 

 6.40  105 J

6.40  105J 4 1.60  105J

Doubling the speed quadruples the kinetic energy.

12.

(a)

P=



mgh t

 70.0 kg   9.8 2  10.0 m  m s   10.0 s

 kg   2   m  70.0  9.8 10.0   s   m

10.0 Nm  686 s  670 W

s

(b)

670 W W 746 hp 

670 746

W hp  1 W

 0.90 hp

4

Heat and Temperature

Contents The Kinetic Molecular Theory Molecules Molecules Interact Phases of Matter Molecules Move Temperature Thermometers Thermometer Scales Heat Heat as Energy Transfer Measures of Heat Specific Heat Heat Flow Energy, Heat, and Molecular Theory Phase Change Evaporation and Condensation Relative Humidity Thermodynamics The First Law of Thermodynamics The Second Law of Thermodynamics The Second Law and Natural Processes

Overview

Heat and temperature, like energy and work, are words that students often use in everyday language in which their scientific meaning can be different than typical usage. This difference is well poised to interfere with students‘ understanding the concepts in this chapter. Students will benefit from an explicit discussion of this issue. The chapter presents a short historical development of ideas about heat, then develops the theoretical basis for the modern understanding of temperature and heat. Concepts of heat and the kinetic molecular theory are closely linked, and observations of heat interactions provide evidence in favor of the kinetic theory. In turn, the particle nature of matter becomes more realistic from the quantitative and qualitative evidence provided by heat. The modern understanding of heat, which is derived from thermodynamics, is that heat is a measure of the amount of internal energy transferred from one object or system to another object or system. Heat corresponds to work at a molecular level and they are not considered separate concepts.

Energy, work, and heat are measured in units of joules in science classes for science majors. The units of calories and Btu‘s are also discussed in this text for nonscience majors because these are common heat measurements in everyday use. A measured amount of heat will affect the temperature of any substance, but the change in temperature will vary with the substance. Each substance has its own specific heat, which is usually smaller than that of water.

Thus, less heat (internal energy) is required to raise the temperatures of these substances and, as they cool, they release less heat, or release less internal energy, than water. Conduction, convection, and radiation are important concepts of heat flow, and understanding them will become more important as present-day lifestyles place more and more demands on the energy supply.

Suggestions 1. A Brownian motion device and a microscope projector (perhaps borrowed from the zoology department) can be used to show the random kinetic energy involved in Brownian motion. A few crystals of potassium permanganate in a tall, graduated cylinder filled with water can be situated so it will remain undisturbed for a week. The resulting diffusion of the purple color can be related to the observed Brownian motion. Alternatively, there are many well-done Brownian motion demonstrations are available as online, Internet videos.

2. Linear expansion of heated solids can be demonstrated with a bimetallic strip, which can be compared to the coiled strip in many home thermometers and thermostats. An air thermometer can be demonstrated with an inverted Florence flask with a one-hole stopper and glass tube. The flask is supported by an iron ring on a ring stand with the glass tube extending into a beaker of colored water. When the flask is warmed by your hand air bubbles come from the tube in the water, providing evidence of expansion of the air inside the flask. As the flask cools water is forced into the tube by atmospheric pressure. The water level inside the tube is highly sensitive

to temperature variations but is not used as a thermometer because it is also highly sensitive to atmospheric pressure variations.

3. The concept of specific heat can be demonstrated by simultaneously heating a block of iron and an equal mass of water over burner flames. When the water is warm a few drops transferred to the iron will sizzle, indicating the much higher temperature of the iron. The specific heats of water and iron can then be compared and discussed.

4. The concepts of conduction, convection, and radiation may be illustrated with the demonstration conductometer, the convection box, and the radiation outfit, all available from scientific supply houses. Point out that the oven advertised as a ―convection oven‖ means forced convection. All ovens heat food through natural convection. A ―convection oven‖ has a fan, which mechanically mixes the air.

5. The latent heat absorbed or released during a change of state is interesting to students. Ice cubes at 0˚ C placed in a glass of water at 0˚ C absorb latent heat as they melt, and no temperature change is observed during the melting process. Heat obtained from the surroundings is required to melt the ice at 80 cal per gram. When water freezes the same amount of energy (latent heat) is released. Since there is no temperature change, latent heat is not involved in kinetic energy. Since the same amount of heat is released during freezing as is absorbed during melting, the heat must be ―hidden‖ as changes in potential energy. Relate this energy transfer to the energy required to create potential energy in a mechanical system (lift a chair to a tabletop; ice melts). The chair (and the liquid water) has more potential energy as a result of the work done (lifting the chair; separating the molecules from the solid state). When the chair is returned to the floor (the liquid water freezes), the potential energy (latent heat) is released.

6. The concept of relative humidity can be readily demonstrated with a collapsible plastic cup available from most drug stores. Half fill a fully extended cup with water, then ask the class what percent of the cup is filled. The analogy is that air has half the water it can hold at a particular temperature (50 percent relative humidity). Drop the upper ring on the cup, which reduces the capacity about 25 percent (depending on the particular cup used). This is analogous to reducing the air temperature, which reduces the air capacity to hold water. Because of dropping the ring, the cup is now 75 percent full (75 percent relative humidity). Drop the next upper ring and the cup is now 100 percent full, an analogy to saturated air and 100 percent humidity. Drop another ring and water will spill to the floor. Students will probably exclaim ―rain!‖ to which you will ask if rain falls from a clear sky. Point out that the falling water represents condensation, which results in dew or the formation of a cloud. Rain falls from clouds, not clear air.

7. Relationships between heat, boiling, evaporation, condensation, air pressure, and atmospheric pressure can be demonstrated with an ordinary aluminum soda can and a burner. Rinse the can and pour several centimeters of water into the can, asking the class to note how much water you are pouring into the can. Using laboratory tongs, hold the can over a burner flame (with the palm side of your hand up) until the water boils for a minute. Point out that the visible mist coming from the can is not steam (gases are invisible) but is condensed water vapor just like the droplets

in a cloud. Quickly invert the can in a large beaker full of cool water. The can will be immediately crushed with a loud pop. As you raise the can from the beaker of water, it will be obvious that more water is now running from the can than you poured in originally. Ask the students to explain what happened.

8. Additional demonstrations: (a) Measure the temperature of equal amounts of cold and warm water, then mix them together in an empty glass beaker. Take another temperature reading, showing the final temperature is nearly midway between the two initial temperatures. Discuss Q, m, c, T, and why the temperature was not exactly midway. (b) Commercial demonstration devices are available to compare the rates of heat conduction in metals. One such device, for example, has rods of iron, copper, aluminum, nickel, and brass that are set into a metal ring. A thumbtack is attached to the end of each bar with candle wax and the center ring is heated. (c) Commercial demonstration devices are available to show convection in a smoke box. One such device consists of a box with two openings with chimneys. One side is of a transparent material such as glass or plastic. A small lighted candle (or other heat source) is placed under one chimney and a smoke source is held just over the opening not above the candle. Convection currents can be observed as the smoke moves down one chimney, through the box, and up the other chimney over the heat source.

For Class Discussions 1. A metal lid is stuck on a glass jar. What will help you open the jar? a. Heat it under running water. b. Cool it. c. Heat it under running water, then quickly cool it. d. Vigorously shaking the jar to increase its temperature.

2. If you add heat to liquid water, then the temperature a. always increases. b. sometimes decreases. c. might stay the same.

3. The cheese on a hot pizza takes a long time to cool because it a. is not elastic. b. low specific heat. c. high specific heat. d. has a white color.

4. The great cooling effect produced by water evaporating comes from its high a. conductivity.

b. specific heat. c. latent heat. d. transparency.

5. Anytime a temperature difference occurs, you can expect a. cold to move where it is warmer, such as cold moving into a warm house during the winter. b. heat movement from cold to warmer regions. c. heat movement from high temperature regions. d. no energy movement unless it is warm enough.

6. The specific heat of a copper wire is roughly three times as great as the specific heat of gold.

Which of the following is true? a. If the same amount of heat is applied to equal masses of gold and copper, the copper will become hotter. b. Copper heats up three times as fast as gold. c. A piece of copper stores three times as much heat as the same mass of gold at the same temperature. d. The melting temperature of copper is roughly three times that of gold.

7. Compared to sea level, water at a high-elevation boils at a. a lower temperature. b. a higher temperature. c. 100°C 8. Turning up the heat under a boiling pot of water will a. shorten the cooking time by making it hotter. b. cause no change in the temperature of the water. c. require more time to cook because the water is boiling faster.

9. The heat death of the universe is a time in the future when the universe is supposed to a. have the same temperature. b. have a very high temperature everywhere in the universe. c. freeze

Answers: 1a, 2c, 3c, 4c, 5c, 6c, 7a, 8b, 9a

Answers to End of Chapter Concept Questions 1. Temperature is a measure of the average kinetic energy of the molecules of a substance. Heat is the total internal energy of the molecules involved in an energy transfer.

2. As the temperature of a solid increases, the vibrations of the individual molecules become larger. When these vibrations become larger, the average distance between the molecules increases to accommodate these larger oscillations, and the solid expands. In a liquid or a gas, the individual molecules move faster as the temperature increases, and the collisions between individual molecules become more violent. Since the molecules are moving faster, they move farther apart as they travel a larger distance in the time between collisions.

3. Tight packing would tend to decrease the insulation value of glass wool because it would squeeze the wool together and give the heat more paths to travel. It is the presence of many

small pockets of air, with unattached molecules, that gives glass wool and other similar insulation materials their insulating properties.

4. The vacuum between the walls prevents heat transfer by means of convection or conduction, while the silvered walls reflect radiated energy back into (or away from) the food, preventing energy transfer by radiation.

5. Cooler air is denser than warmer air. This denser air weighs more per volume than the warmer air and pushes the warmer air out of the way as it sinks down to its lowest level. The warmer, less dense air sits on top of the cooler air because it weighs less per volume.

6. Air is not very dense and conduction is not very efficient at transferring energy because the molecules are much farther apart than they are in solids or liquids.

7. The metal is more efficient at conducting heat away from your hand than wood, so it feels cooler because your hand senses heat leaving your body.

8. Condensation occurs when more vapor molecules are returning to the liquid state than are leaving the liquid state. When a water vapor molecule joins a group of liquid water molecules, it has to give up its latent heat of vaporization. This heat is transferred to the surrounding air molecules such as the air in the bathroom.

9. The 10 pounds of ice provide more cooling because as the ice undergoes the phase change into water, it absorbs heat. Ten pounds of ice water simply absorbs heat according to the value of its specific heat until it reaches room temperature and therefore absorbs less heat.

10. Water condenses out of the air onto the cooler surface of a glass because the air near the glass is cooled, lowering its temperature to the dew point. Since the warmer air can hold more water vapor in the summer, it would have more water vapor to condense. Therefore, you would expect more condensation in the summer.

11. One-hundred-degree Celsius steam contains more energy (540 cal/g) than 100°C water, so the steam burn would be more severe.

12. Cooling of air reduces the capacity of air to hold water vapor. Relative humidity is a ratio of water in the air to how much water it can hold. Thus, a decrease of capacity increases the relative humidity, even when the amount of water vapor in the air is constant.

13. Table salt takes the shape of a container and has a definite volume. These are the properties of a liquid.

14. Similarities – both heat and temperature involve internal energy, the energy of molecules.

Difference – temperature involves an average of the random kinetic energy of the molecules in a body; heat involves the total internal energy, both kinetic and potential. Temperature of a body can be measured anytime; heat can be measured only by adding it or removing it from a body.

15. Clarifying the meaning of these words will show that answers will vary.

16. Analysis will show that copper is more practical and more energy efficient.

17. Developing criteria for evaluation will depend on the local climate.

18. Analysis will show that moving heat without the latent heat of vaporization would restrict the movement to that would take place by conduction, convection, or radiation, which would not be practical.

19. Evaluating and pursuing an alternative concept of the future will result in answers that vary but should be logical.

End of Chapter Group B Solutions 1.

5 TF  32  9 5   98  32  9 5   66  9  37

TC 

TK = TC + 273 = 37 + 273 = 310 K 2.

Q  mcT  kcal    0.25kg   0.22 10.0C  kgC    0.55 kcal

3.

Q  KE and KE  Q      

1 2 1 mv  Q  mv 2 2 2

1 2 mv 2  1 km m 1.00 hr  1.000.0 kg   90.0  1, 000   2 hr km 3, 600 s   m  500.00 kg   25.0  s   m2 500.00 kg  625 2 s kg  m 312,500 2  m s 313, 000 J

Q  313, 000 J 

1.00 cal 4.184 J

2

2

 74, 700 cal  74.7 kcal

4.

Q  KE and KE 

Q  mcT  mcT 2

T



1 2 1 mv  Q  mv 2 2 2  1 2   1.00 cal    mv    1 2 2   4.184 J   mv  T  2 mc

1 m 1.0kg   5.0  1.00 cal  1.00 kcal 2 s    1, 000.0 cal  kcal  1.0 kg   0.11  4.184 J   kgC  

 0.027 C

5.

Q  PE and PE  n  mgh  where n  number of times up stairs  Q  n  mgh  and n 

n 

6.

1.00 kcal   4.184 

Q mgh

J   kcal 

 0.71 times

m  60.0 kg   9.8 2  10.0 m  s  

Q  mcT  kcal    50.0  103 kg   0.056 89.0C  20.0C  kgC    0.19 kcal

7.

Q  mcT  m 

Q c T

190.0 kcal  kcal   1.0 kgC   0.75 C   

m 

 0.25 kg

8.

W P mcT W  Q  t  P  cal   250.0 g   1.00 100.0C  20.0C  gC   t  J   1.00 cal    300.0   s   4.184 J   P 

W t

 t 

 279 s, and 279 s s 60.0 min



279 60.0

s min  1 s

 4.65 min

9.

Q  mcT  c  c 

Q m T

2.6 kcal  0.2000 kg  65 C 

 0.20

kcal kgC

10.

Q1  mcT  cal    500.0 g   1.00 80.0C  gC    4.00  104 cal Q2  mLv  cal    500.0 g   540.0 g    2.70  105 cal QTotal  Q1  Q2

  4.00  104 cal    2.70  105 cal   3.10  105 cal  310. kcal

11.

Q1  mcT  kcal   1.000 kg   0.48  20.0C  kgC    9.6 kcal Q2  mLv  kcal   1.000 kg   540.0 kg    540.0 kcal Q3  mcT  kcal   1.000 kg   1.00 10.0C  kgC    10.0 kcal QTotal  Q1  Q2  Q3

  9.6 kcal    540.0 kcal   10.0 kcal   559.6 kcal

12.

Q1  mcT  kcal    250.0 kg   0.028   308.0C  kgC    2,156 kcal Q2  mLf  kcal    250.0 kg   5.5  kg    1,375 kcal QTotal  Q1  Q2

  2,156 kcal   1,375 kcal   3,531 kcal

5

Wave Motion and Sound

Contents Forces and Elastic Materials Forces and Vibrations Describing Vibrations Waves Kinds of Waves Waves in Air Hearing Waves in Air Describing Waves Sound Waves Velocity in Air Refraction and Reflection Interference Energy and Sound Loudness Resonance Sources of Sounds Vibrating Strings Sounds from Moving Sources

Overview Students experience sound every day, but they might not have ever considered how scientists can accurately describe it. Because sound seems tangible, sound can serve as an ideal way to present velocity, frequency, and wavelength as well as other measurable characteristics of all types of waves as the movement of energy from one place to another. Curiously, some attributes of sound are subjective. Students should be presented with repeated examples and experience to begin to describe the variance present in sound waves, such as pitch, loudness, and quality. With proper demonstrations, students can quickly learn to determine the subjectivity of these measures and ascertain which students are musically inclined or trained.

The chapter begins with vibrations and the characteristics of vibrations, then logically proceeds to the waves, or disturbances, that are produced by these vibrations. Characteristic wave terms are introduced, then used to explore some of the more interesting sound phenomena

that students can relate to. Students are familiar with echoes, but many have no conception of their cause. It is subjective if a listener hears a reverberation or an echo. There are many methods by which various musical sounds are produced. All sources of musical sounds are represented in the chapter, along with some theory behind some musical notes. The Doppler effect applies to all waves, but it is easier to discuss and to demonstrate with sound. Any constant sound that is in motion relative to the listener will produce the effect. Light also undergoes the Doppler effect, and this application is discussed in other chapters.

Suggestions 1. Start with a typical digital music player and demonstrate the different ways that digital music can be changed without trying to quantitatively describe the nature of sound. Then, to illustrate how vibrating matter creates sound, place one end of a ruler, metal strip, or meter stick on the edge of a desk. Hold the end down securely and pluck the opposite end. Practice will enable you to determine proper adjustments. Students should also relate the frequency of the sound produced to the length and rate of the vibrating object. The vibrations of a struck tuning fork are difficult to observe. They can be illustrated by holding a vibrating tuning fork in one hand and a sheet of paper in the other, lightly touching the vibrating end against the paper. A dramatic (and somewhat humorous) illustration is obtained by plunging a vibrating tuning fork into a beaker of water.

2. Vibrate your arm up and down as you hold a piece of chalk against the chalkboard, walking along the length of the board. Point out that the wave trace obtained is a graph of the vibration and not in itself a wave. Compare the wave traces obtained with more rapid vibration (greater frequency) and more energy (greater amplitude). Ask if anyone hears your vibrating arm, which leads to a discussion of audible waves.

3. A twenty-foot-long or so one-inch diameter helical spring is ideal to demonstrate both longitudinal and transverse waves. Shaking the coil from side to side produces a transverse wave, while holding the spring taut and releasing a group of bunched-up coils produces longitudinal waves. The motion of a string tied to the center part clearly shows the characteristic disturbances produced by these two kinds of waves. The coil can also be used later to illustrate standing waves at several different frequencies.

4. A ―trick‖ demonstration involving forced vibrations maintains interest and helps teach the basic wave terms. State that you will illustrate what happens to a sound wave when it is inside a container. Strike a tuning fork and hold it in one hand with the rod end near the tabletop but covered by your hand. Tell the class that you are going to grasp a wave by its crest, then drop it into a beaker (or some other container). Act as if you are grasping a crest with your thumb and finger near the end of the vibrating tuning fork, then act as if you drop the wave into the container. The trick here is to touch the base of the rod firmly (but quietly) to the tabletop as you ―release the wave‖ over the beaker with your other hand. With a little practice, it will seem as if

there is an increase in loudness as you ―drop‖ the wave. You may need to do this several times before someone catches on. You now have the class's undivided attention as you explain the concept of forced vibrations—that the tuning fork touched to the table starts the whole table vibrating. This is an ideal place to reinforce the conservation of energy concept. Compare the time that the whole table vibrates (with a louder sound) with the time that the tuning fork only vibrates (with a softer sound).

5. A signal generator can be used to illustrate the frequency ranges that students of various ages are able to hear. Two signal generators can be used to illustrate the beat concept. Hooking the generators to an oscilloscope provides a visual representation of what they are hearing.

6. Additional demonstrations: (a) Do the classic demonstration showing that the transmission of sound requires a medium.

Place an electric bell inside a vacuum pump bell jar, evacuating the jar as the bell rings. Note the bell hammer continues vibrating as the sound level dies out. Stop the pump and restore air to the jar to hear the bell again. (b) Use citizen band radios or mobile telephones to measure the speed of sound over a distance.

One student signals the beginning of a sound over the radio or telephone and a student at the other end starts a stopwatch at the signal, stopping it when the sound is heard. The signal used will depend on what is available locally. Measure the distance and make the correction for temperature. (c) Use a commercial demonstration device that varies the height of a flame with the frequencies of sounds. (d) Demonstrate resonance with commercial resonator boxes fitted with identical frequency sounding bars or tuning forks. (e) Demonstrate beats with commercial resonator boxes fitted with tuning forks that are 1 Hz apart in frequency. (f) Ask the class to close their eyes, then drop a previously hidden metal drill bit. Ask the class to open their eyes as you hold up the bit and a board, asking which you dropped. Explain the concept of natural frequency.

For Class Discussions 1. How can astronauts talk to one another on the Moon, where there is no air? a. Air is not needed if one is standing with heavy boots on something solid. b. By radio transmissions. c. By staying inside a pressurized space suit. d. This is impossible; they could not talk.

2. An airplane moves over your location at a speed greater than the speed of sound, so you should hear a. nothing since the plane was moving faster than sound. b. nothing, then a sonic boom, followed by the distant sound of engines. c. a sonic boom only at the instant the plane breaks the sound barrier, then silence. d. two sharp sonic booms, followed by silence.

3. Does a high frequency sound travel faster than a low frequency sound? a. Yes. b. No. c. Sometimes it does, depending on the conditions.

4. What happens if a source is moving toward you at a high rate of speed? a. The sound will be traveling faster than from a stationary source. b. The sound will be moving faster only in the direction of travel. c. A higher frequency will be heard by you only. d. A higher frequency will be heard by all observers in all directions.

5. What happens if you are moving at a high rate of speed with a sound source? You will hear a. a higher frequency than people you are approaching. b. the same frequency as people you are approaching. c. a frequency that is the same as from the source when it is not moving.

6. During a track and field competition event, the time difference between seeing the smoke from a starter's gun and hearing the ―bang‖ would be less a. on a warmer day. b. on a cooler day. c. if a more powerful shell is used. d. if a less powerful shell is used.

7. At the same temperature, the gas that would carry a sound with the greatest velocity would be a. oxygen. b. hydrogen. c. carbon dioxide. d. The velocity would be the same in each gas.

8. As you go up a mountain the air becomes less dense, and with everything else constant, the overall velocity of sound a. increases steadily with increasing altitude. b. decreases steadily with increasing altitude. c. increases slowly at first, then rapidly with increasing altitude. d. does not change.

Answers: 1b, 2b, 3b, 4c, 5c, 6a, 7b, 8d.

Answers to End of Chapter Concept Questions 1. A wave is a disturbance that moves through a medium such as a solid or the air.

2. No, because there is no force acting on the air to return it to its original position after the wave has dislocated it.

3. Loosen. Since the beat frequency depends upon the difference between the two frequencies, you wish to go in the direction of fewer beats per second.

4. There is no medium such as air to transmit sound on the moon.

5. The condition where the frequency of an external force matches the frequency of an object is resonance.

6. Gas molecules have a greater kinetic energy and move faster in warm air than in cold air.

These molecules are able to transfer an impulse from one molecule to the next faster.

7. Longer wavelengths have lower frequencies. Since the velocity of sound is equal to the product of the frequency times the wavelength, the velocity is a constant.

8. The energy of the sound wave is eventually dissipated into heat.

9. The presence and strength of various overtones determine the characteristic sound of a musical note.

10. The sonic boom is from the building up of a pressure wave in front of the moving aircraft.

Since this pressure wave is present as long as the plane is moving faster than the speed of sound, the aircraft continually makes a sonic boom.

11. An echo is the return of a sound wave to its source after the wave has been reflected.

12. They all produce standing waves or resonance in whatever is oscillating.

For Further Analysis 13. If the speed of sound decreased with frequency, all the musical notes would become separated with higher frequencies arriving first.

14. Similarities – both longitudinal and transverse waves are mechanical disturbances that move through matter. Differences – In a longitudinal wave the disturbance acts in a direction parallel to the direction the wave is moving; In a transverse wave the disturbance acts in a direction perpendicular to the direction the wave is moving. Examples will vary.

15. Possible explanation: The empty room has more echoes that bounce around and garble the sound.

16. Starting with two distinct tones, a fast beat develops, which slows as the frequencies approach each other while tuning the instrument. It slows to a single pitch when tuned.

17. Two identical sounds moving through the air that are 180 degrees out of phase will cancel each other.

18. Vibrations are the sources of all sounds, which is supported by observation as well generalizations.

19. Unlike objects, sounds waves have the ability to pass through one another.

20. If the marching band happens to match the natural frequency of the bridge, resonance could start the bridge swaying and possibly cause damage.

End of Chapter Group B Solutions 1.

v  f   440.0 Hz    78.0 cm   3.43  104

2.

cm (or 343 m/s) s

v  f 1  v   256.0   2  65.23 cm  s   3.340  104 cm / s (or 343.0 m/s)

3.

 a  T  5.0s b

f 

1 T



1 5.0s

 0.20 Hz

4. v  f   

v f

m s   1 750.0 s 343.0 m s   750.0 s 1 343.0

 0.4570 m

5.

(a)

v 

f 

 20.0 Hz 17.2 m   344 m / s   200.0 Hz 1.72 m   344 m / s   2000.0 Hz  0.172 m   344 m / s   20, 000.0 Hz  0.0172 m   344 m / s

v  (b)

v

(c)

v

(d)

v

6.

v

d  d  tv t m  = 10.0s   337  s    3370 m 3370 m  1658 m 2  1660 m

7. v 

d t

d v 5280 ft  ft 1151 s  4.59 s

 t 

8. v  f   

Air:

ft s   1 600.0 s  1.81 ft 1087.0

ft s ft 4920.0 s   1 600.0 s  8.2 ft v  4920.0

Water:

6

Electricity

Contents Electric Charge Measuring Electrical Charge Measuring Electrical Force Electric Current Resistance AC and DC The Electric Circuit Electrical Power and Work Magnetism Moving Charges and Magnetic Fields Magnetic Fields Interact A Moving Magnet Produces an Electric Field

Overview

v f

f  600.0 Hz

Most students have had considerable experience with battery life in various personal technologies, but almost no formal experience thinking about electricity as a quantitative entity.

The biggest cognitive challenge here is that most student enter the class mistakenly thinking of electricity as a tangible substance that moves, can be stored, and can evaporate. This chapter presents the basic concepts of charge and current, and students develop the understanding that electricity is another form of energy perfectly analogous to other forms of energy. It begins by discussing static electricity, which is basic to any study of electrical phenomena, and some very basic atomic theory. Static electric charges are ―at rest‖ but are produced by an excess or deficiency of electrons brought about by friction, generally between unlike insulators.

Electric current is defined as the flow of charge rather than the flow of electrons. Current in a conductor approaches the velocity of light, a rate of movement not possible for an electron moving from atom to atom under ordinary circumstances. To move an electric charge against the electric field of other electrons requires work, creating electric potential energy that is in every way analogous to gravitational potential energy. In either case work is done against a field to develop the potential energy. The same quantity of work is realized (disregarding losses) when the potential energy is utilized at some place in a circuit. When a joule of work is done on a coulomb of charge to move it against an electric field, the difference in potential between the points is a joule per coulomb. This is called a volt. Students seem to have two difficulties with this concept, (1) that a coulomb is a quantity of charge and (2) that volt means work per charge.

They must be helped over this difficulty and understand that a current of one coulomb per second is called an ampere.

Understanding voltage and amperage is necessary before they can be combined to discuss resistance (Ohm's law), work, and power meaningfully. Avoid the temptation to discuss the differences in resistors, voltage, and current in series and parallel circuits unless students are majoring in programs of a technical nature.

Magnetism and its properties are of interest to students, and this chapter presents the major characteristics of magnets and magnetic fields. The fundamental relationship between electric and magnetic fields is discussed and then applied to many common phenomena in the environment and to technological devices. The generation and conditioning of alternating current between its source and its consumption is considered a primary way of transferring energy long distances.

The active cutting of the imaginary lines of force that surround a magnet by a conducting wire causes current to flow in the conductor. If the direction of the moving magnet is reversed, the current flow also reverses. This constant reversal of the moving magnet produces alternating current. Home appliances operate on 60 hertz alternating current. A coil of wire rotating about the poles of a magnet also would produce alternating current. Devices that convert mechanical energy into electrical energy are called generators. Motors convert electrical energy into mechanical energy. Except for efficiency loss due to resistance and other uncontrollable factors, a combination of the two devices could produce a seemingly endless supply of electricity.

To reduce energy loss from resistance through heating, alternating current is stepped up by transformers, since the current is inversely proportional to voltage if power is held constant.

Alternating current is stepped back down before it enters the home. Direct current cannot be stepped up efficiently without complex circuitry, it cannot be stepped down as easily as alternating current, and it is more costly to generate than alternating current.

Suggestions 1. Demonstrate static electric phenomena with hard rubber rods, cat fur, glass rods, and silk cloth. Here is a situation in which modern Internet videos can be very helpful, particularly if you live in an area of high humidity. Students need repeated experiences with how static electricity can be generated, the identity of the charge that accumulates on an electroscope, how like and opposite charges affect each other, and how static electricity accumulates on the surface of a conductor.

2. Bring a negatively charged rod near a small but steady stream of running water and note how the water is attracted. Ask the class what the charge of the water appears to be. Bring a positively charged rod near the stream of water and note the effect. These observations point out how both electric charges affect the neutral charge of the water.

3. Demonstrate Ohm‘s law with resistors of known values connected to a large demonstration ammeter and voltmeter. Take readings quickly to avoid heating (and changing the value of the resistors), and let the class do the calculations.

4. The relationships between amperage, voltage, work, and power are popular among students when applied to the cost of using certain electrical appliances. For example, how much does it cost to use a 1,300 watt hair dryer for 15 minutes?

5. The magnetic field of a magnet can be demonstrated to a large class with an overhead projector. Place a clear plastic sheet over a bar magnet. Sprinkle iron filings on the sheet and tap the sheet with your finger. Arrangements that show attraction and repulsion between two magnets can also be dramatically illustrated in this manner.

6. Use a ring stand and clamps to support a length of stiff copper wire vertically through the center of a flat piece of cardboard. Sprinkle iron filings around the wire, then connect the ends to a dry cell or power supply. Tap the cardboard, then disconnect the power supply immediately when the concentric circles form. Use the left-hand rule to determine polarity of the magnetic field.

7. Magnetize a large paper clip (or soft iron nail) by placing it on one end of a strong bar magnet, then tapping it. Remove the clip from the magnet and show that it is magnetic by bringing it near a second, unmagnetized paper clip. Throw the magnetic paper clip (nail) hard against the floor, then check it again with a different paper clip to show that it has lost most of its magnetism. Explain the entire procedure with the magnetic domain concept.

8. Connect a coil of wire to a large demonstration galvanometer and move the coil toward and away from the magnetic field of a strong magnet (e.g., from a speaker). Show that the needle of the galvanometer moves in one direction when the wire coil moves toward the magnet and in the other direction when the wire coil moves away from the magnet. Illustrate that the movement is relative by now moving the magnet toward and away from the stationary coil of wire.

9. The operation of an electric motor or generator can be demonstrated with the use of a St. Louis motor, a variable direct current power supply, and a small light bulb. The adjustments of the magnets are critical but easily accomplished. Check to be sure that the bar magnets are installed with the poles of each magnet turned opposite the poles of the other.

10. Additional demonstrations: (a) Demonstrate the nature of static electricity with suspended pith balls, electroscopes, a rubber rod rubbed with cat‘s fur, and a glass rod rubbed with silk. Suspend inflated rubber balloons with thread, then give them a negative charge by rubbing with cat‘s fur. (b) Use a small hand-turned generator to demonstrate that work is done to generate electric current. Vary the speed to show that the current generated is directly proportional to the work done. (c) Demonstrate Ohm‘s law using a large ammeter and voltmeter with resistors of known values. (d) Show the relationship between a magnetic field and polarity by sprinkling iron filings on a transparent sheet of plastic over a magnet. Ask students to predict shape of fields around horseshoe magnets, bar magnets, and others, then check their predictions. (e) Display rheostats, relays, meters, telephone parts, speakers, and other devices that work with electromagnets. (f) Display a simple St. Louis type motor connected to a dry cell to show how current moving through the motor can do work. Replace the dry cell with a galvanometer, then give the armature several whirls to show that current can be generated by doing work.

For Class Discussions 1. Three pieces of amber are hung from threads, then each is charged by rubbing piece A with fur, piece B with silk, and piece C with nylon. It is now observed that piece A and B repel each other and that Piece B and C repel each other. This means a. pieces A and C have opposite sign charges. b. pieces A and C have the same sign charge. c. piece B does not have a charge. d. all three pieces have the same sign charge.

2. If the pieces of amber in the previous question acquired a positive charge, the each of the rubbing materials a. acquired an equal negative charge.

b. acquired a positive charge, too. c. acquired a charge, but not equal and opposite to the amber.

3. When a substance acquires a charge from an excess of electrons, would the mutual repulsion repel them uniformly throughout the substance? a. Yes. b. No. 4. Considering the separation of charges, is it possible to have a high voltage without any current? a. Yes. b. No.

5. Which of the following is a measure of electrical work? a. kilowatt b. C c. kWh d. C/s 6. A bird lands on a non-insulated, 80,000-volt high line. Will it receive a shock? a. Yes. b. No. 7. When an object acquires a negative charge it actually a. gains mass. b. loses mass. c. has a constant mass.

8. A positive and a negative charge are initially 2 cm apart. What happens to the force on each as they are moved closer and closer together? It a. increases while moving. b. decreases while moving. c. remains constant.

9. The current in the secondary coil of a transformer is produced by a a. varying magnetic field. b. varying electric field. c. constant magnetic field. d. constant electric field.

10. The nature of the force that enables an electric motor to do its job is a. electric. b. magnetic. c. electromagnetic

Answers: 1d, 2a, 3b (just on the surface), 4a, 5c, 6b (no voltage difference on bird), 7a, 8a, 9a, 10b.

Answers to End of Chapter Concept Questions 1. The balloon has a net charge as a result of being rubbed. When the balloon is brought near a wall, the net charge on the balloon moves electrons around in the wall. As a result, a small

region near the balloon has a net charge of opposite sign than the balloon. The overall wall is still electrically neutral; there are now small regions that have net charges. The force from the opposite signed charges in the balloon and the wall causes the balloon to stick to the wall. There it will stay until enough charge has leaked away to cancel the charge on the balloon.

2. Excess charge is building up on your body from the carpet as you walk across it. When a metal object is touched, the charge flows out of your body, through the lower resistance of the metal. It finds a path into the ground, which supplied the charge to make up for what you removed from the carpet.

3. An electron carries a negative charge and can be moved to and from objects relatively easy.

Since electrons cannot be divided into parts that can move separately, the smallest charge it is possible to have or to move is the charge of one electron. The charge of one electron is referred to as the fundamental charge.

4. The electrons move rapidly inside a wire bouncing against each other like molecules in a gas.

Since so many collisions occur, an individual electron cannot move from one end of a wire to another rapidly. The electric field inside the wire, which exerts a force on the electrons, can move rapidly though the wire because it does not require something to carry it. The force from the electric field gives the electrons a drift velocity, which constitutes a current.

5. A kWh is work multiplied by time. Since a watt is energy per time, a kWh is a unit of energy or work.

6. In direct current (dc), the current always flows in a single direction. In alternating current (ac), the flow of current changes direction with a regular frequency.

7. A magnetic pole is a region where the force of magnetic attraction seems to be concentrated.

The pole that seeks, or points to a generally north direction, is called a north pole, and the other pole is called a south pole.

8. In an unmagnetized piece of iron, the magnetic domains are pointing in random directions such that the net field is zero. In a magnetized piece of iron, most of the domains are aligned so that their fields add to make a larger field.

9. If the voltage is small, the current is large for a particular amount of power. Increasing the voltage decreases the current. Large currents promote many collisions of electrons inside the wire with other electrons and positive ions. Each collision takes energy from the electric field, diverting it into kinetic energy of the positive ions and heating the wire, so there are fewer power losses with lower currents. Thus a higher voltage means less power loss since the current is lower.

10. The electromagnetic generator uses induction to generate a current in loops of wire moving in a magnetic field. Electrons in the loops of wire are forced toward one end by the magnetic field, which sets up a potential difference.

11. The earth's north magnetic pole is actually a magnetic south pole located near the geographic North Pole.

12. The electron is moving, creating its own magnetic field. The interaction between the magnetic field of the electron and the external magnetic field creates a force on the electron,

causing it to move.

13. The generation of electricity involve much more than the movement of electrons, including the establishment of electrical potential between two points in a circuit, the creation of an electric field as a result, and the movement of electrons as caused by the field.

14. Similarities – both are electric fields moving through a conductor, which carries energy.

Differences – In alternating current the field moves electrons back and forth; in direct current the field moves electrons in one direction.

15. Answers will vary, but it does appear that people should be warned about amps, not volts.

16. Answers will vary, but should be logical and supported by identified insights, beliefs, and arguments.

17. Answers will vary, but should show the understanding that solar energy is free, but the bucket to catch it is very expensive.

18. Similarities – both are fields, which is a change of the condition of space around an electrical charge or magnetic field. Differences – an electrical field is found around a charge; a magnetic field is found around a magnet or current carrying wire.

End of Chapter Group B Solutions 1.

q  ne coulomb    1.0  109 electrons  1.60  10 19  electron    1.6  1010 C

2.

I 

q C  2.0 amp  2.0 t s

3.

V  IR  R  R 

V I

120 V 0.83A

 145   150 

4.

V  IR V  V   3.33A   60.0  A  2  2.00  10 V

5.

(a) V  IR  I  I 

V R

12.0 V 10.0 

 1.20 A

(b)

P  IV  1.20 A 12.0V   14.4 W

6.

V  IR  I  I 

V R

120.0 V 192 

 0.625 A

P  IV   0.625A 120.0V   75.0 W

7. hr  720 hr day

t  30 days  24

cost 

 work  time  rate 

w kw $0.10   60W  720 h     kWhr   w 1, 000 kw  $4.32 1, 000

8.

(a)

P  IV  11.5A  240.0V   2,760 W

(b)

2,760 W 2,760  746 W 746 hp

W hp  1 W

 3.7 hp

9.

2.0 hp 

cost 

746 W hp

 work  time  rate  1, 000



 1, 492 W

w kw

1, 492W 18 h  

$0.10    kWhr 

1, 000

w kw

 $2.69

$2.69/day  30 day/month = $80.70/month

10.

P V

P  IV  I  J s I  J 120.0 C  10.83A 1,300.0

Since 2 times 10.83 A is 21.66 A, two devices will clearly overload a 15 A circuit.

11.

(a) Vp Np



Vs 

Vs N  Vs  s  Vp Ns Np 1,500 loops 120V 100 loops

 1,800 V

(b)

Vp I p  Vs I s  I s  Is 

Vp Vs

 Ip

120 V  15.0 A 1,800 V

 1.0 A

12. (a) Vp Np



Np 

Vp Vs  Np   Ns Ns Vs 7, 200 V 125 loops 120 V

 7,500 loops

(b)

Vp I p  Vs I s  I p  Ip 

Vs  Is Vp

120 V  36.0 A 7, 200 V

 0.6 A

(c)

P  VI Pin   7, 200V  0.6A   4,320 W Pout  120V  36A   4,320 W

7

Light

Contents Sources of Light Properties of Light Light Interacts with Matter Reflection Refraction Dispersion and Color Evidence for Waves Interference Polarization Evidence for Particles Photoelectric Effect Quantization of Energy The Present Theory Relativity Special Relativity General Relativity Relativity Theory Applied

Overview Electromagnetic waves have many characteristics of interest, including their methods of production, their properties, how they move from one location to another, and their uses in modern technology. A review of wavelength, frequency, and wave velocity as they apply to sound relates these concepts to electromagnetic waves. Sounds are produced by vibrating matter and electromagnetic waves are produced by an accelerated charge. The energy involved in this acceleration results in the various parts of the electromagnetic spectrum, with visible light making up only a small part of the total spectrum. Most importantly, because the term radiation has many misconceptions associated with it, the term is aggressively avoided when teaching nonscience majoring students, and instead the generalized terms ―light waves‖ and ―energy‖ are used as they are more accessible and sufficiently descriptive in this context.

Light and color as light beams that have wave properties is probably a good place to start.

After a consideration of the sources of light, the properties of light are considered from a light ray treatment of the laws of reflection and refraction. The two ways of thinking about light— particles and waves— leads to evidence for both the particle theory and the wave theory of light.

The properties of light that serve as evidence that light is a wave (reflection, refraction, diffraction, interference, and polarization) are considered, followed by the evidence that light is a stream of particles (photoelectric effect and quantization of energy). This leads to the present theory, that light has both wave and particle properties at the same time. Students enjoy a controversy, and this one is based mostly on their everyday notion that light must be either one or the other since everything else in their everyday world appears to be one or the other. However, there is no reason to identify light as being either waves or particles. The modern model of light (and subatomic particles to be discussed in a future chapter) considers light to have both properties at the same time. The model is just that, a model, and it is used because it seems to explain what is observed.

Suggestions 1. Discussion and demonstrations of light and other electromagnetic waves that are not visible are suitable to introduce this chapter. A demonstration of infrared can be accomplished by heating a large piece of iron in a burner flame for several minutes, then holding it close to a radiometer. The radiometer vanes spin more rapidly from the infrared waves emitted by the hot iron. Explain that the radiometer contains some air. The black sides of the vanes absorb infrared waves, which shows up as a slight temperature increase on the blackened surface. The silvered sides of the vanes, on the other hand, reflect the energy without absorbing it. Air particles next to the warm, black surface collide with the surface and rebound with more energy than other particles on the silvered side of the vanes. As a result of the many impulses received from many, many particles on the blackened side the vanes spin in a direction consistent with this explanation.

2. Reflection and refraction can be effectively demonstrated at the same time by filling a small aquarium with water that has been made murky by mixing in some chalk dust. A strong beam of light is aimed downward at a mirror, which reflects the light upward through the aquarium water.

A darkened room and chalk dust (or smoke from a smoke source) makes the light beam visible in the air. The same setup can be used to show total internal reflection by directing the beam at increasing angles until it is totally reflected from the inner surface.

3. A prism can be used to cast the spectrum of sunlight on a wall, leading to a discussion of refraction, dispersion, and color.

4. Diffraction can be illustrated with a classroom spectroscope or small squares of plastic replica diffraction gratings. Students should look toward a light source with the grating, either to the

right or left of center as they rotate the grating until they see a spectrum. A cloth handkerchief that is stretched tightly in front of a laser beam will show a good diffraction pattern.

5. The mnemonic of ―ROY G. BIV‖ helps students remember the spectrum of major colors, although indigo is not totally accepted as a color (has any one seen indigo in a rainbow?).

6. Additional demonstrations: (a) Hold a radiometer near a heated iron block supported on a ring stand to confirm the existence of electromagnetic waves that are not visible to the human eye. Discuss how infrared warms the black sides of the vanes, causing air molecules to rebound with more of a ―kick‖ than they do from the silvered side. This ―kick‖ gives the vanes their motion. (b) Show a spectrum produced by a prism. Mount the prism so the spectrum is cast on a wall. (c) Fill a large beaker or aquarium with water and mix in some chalk dust. Aim a narrow beam of light from a slide projector (or laser) at some angle to demonstrate refraction. (d) Cut inexpensive plastic replica grating into 5 cm squares. Instruct students to handle the squares only by the edges to avoid ―oiling the gratings.‖ Tell them to hold the grating close to one eye, viewing a light source through the grating. They should rotate the grating in 90 degree intervals until a spectrum or spectrum lines are seen. These are usually to the left or right of center. Neon, mercury, and sodium lights are good sources for a line spectrum.

For Class Discussions 1. Light emitted from a hot, glowing wire comes from a. glowing atoms with high kinetic energy. b. fast moving electrons, which tend to glow. c. accelerating electrons. d. oxidation at the atomic level.

2. One of the following behaviors of light means it must consist of waves. a. interference. b. photoelectric effect. c. refraction. d. reflection.

3. Blue stars are emitting ______ energy compared to red stars. a. less b. more c. the same amount of 4. If you look straight down and see a fish under the water, it appears to be a. deeper in the water than it really is.

b. closer to the surface than it really is. c. where it actually is.

5. If you look at a fish that is some distance from you, it appears to be a. deeper in the water than it really is. b. closer to the surface than it really is. c. where it actually is.

6. A fish under the water always appears to be a. larger than it really is. b. smaller than it really is. c. the size it actually is.

7. Can you can distinguish a mirage of water from real water by using polarized sunglasses? a. Yes. b. No.

Answers: 1c, 2a, 3b, 4b, 5b, 6a, 7a (light from water is reflected and thus polarized; a mirage is refracted light and is not polarized).

Answers to End of Chapter Concept Questions 1. The frequency of the wave.

2. Diffraction supports a wave theory of light. A wave front diffracts only if the opening is about the same size as the wavelength. A wave front passing through a large opening will generate wavelets that retain the shape of the wave. A small opening will let the wave generate only one wavelet, which moves out in all directions from the opening.

3. Blue light carries more energy. No, because the energy difference between these two colors is very small. The number of photons determines the intensity of the light.

4. The photoelectric effect supports the particle model, because the effect depended on the frequency and not the intensity of the light. This means that particles of certain energy were creating the effect and not the absorption of a wave.

5. The energy in the light is transferred to the absorbing material.

6. The bluish star is at a higher temperature because higher temperature objects emit more photons of shorter wavelengths (and higher energies) than objects with lower temperatures.

7. Internal reflection occurs when the angle of refraction is equal to or greater than 90°. This occurs more in the diamond because the critical angle depends upon the ratio of the indices of refraction of the air to the stone. The diamond has a very high index of refraction.

8. The hot air above the surface of the highway has a lower index of refraction than the air above it, so light striking the warmer air is refracted upward. This light is interpreted by your brain to be reflected light.

9. Look at the clear sky at an angle of about 90° from the sun. The scattered light from this direction is partially polarized, so if the sky appears to darken as the glasses are turned, the glasses are polarized. If you have a pair of polarizing sunglasses, turn a lens of the unknown pair over a stationary lens of the known, polarizing pair. If the unknown pair is polarizing, light coming through the lens will appear to darken then brighten.

10. Reflected light is slightly polarized. When the polarization of the reflected light is parallel with the polarizing sunglasses, it appears brighter. When the polarization of the light is perpendicular with the sunglasses it appears darker.

11. Planck's findings were revolutionary because they meant that vibrating molecules could only have a fixed amount of energy that could only be multiples of a certain amount called the quanta of energy. All previous experience led everyone to believe that energy could exist in a continuous range of amounts.

12. Neither model totally explains all behavior of light, while a combination of these two models, using each when it is useful, explains all the behaviors of light. There is nothing in conventional experience that behaves as a particle in some situations and a wave in different situations, so the concept is hard to visualize.

13.Answers will vary but should describe reflection as light bouncing from a surface and refraction as the bending of light when passing between two different optical media.

14.Answers will vary in this Socratic discussion attempt to clarify the concept of convection.

15.Answers will vary in this attempt to reason dialogically about the nature of light.

16.Answers will vary in the attempt to compare and contrast the used of convex and concave lenses.

17.E is a quantity of energy, which is a particle property, and f is frequency, a wave property. The equation states they are equal, so it equates particle and wave properties.

18.Same – both are electromagnetic waves that travels at the speed of light. Different radio waves are longer wavelength.

End of Chapter Group B Solutions c  3.00  108

1. (a)

m s

(b) n 

c c  v  v n 

3.00  108

m s

1.00026 m  3.00  108 s

(c) c n

v 

m s  1.00029 m  3.00 108 s 3.00 108

2. v 

d t

d t 3.85  105 km  km 3.00  108 s 5 3.85  10 km s   8 3.00  10 1 km  1.28  103 s

 t 

3. v 

d t

d t 7.83  107 km  km 3.00  105 s km s  261  1 km  261s

 t 

261s 

4.

1 min  4.35 min 60 s

q i  q r  q i  60 from the normal  qr  60 from the normal

5. n 

c v

m s  8 m 2.00  10 s 8 3.00  10 m s   2.00  108 s m  1.50 3.00  108

This is the index of refraction for glass.

6. c  f  f 

c 

and

E  hf

 E  h

c 

 8 m  3.00  10  s   6.63  1034 Js    4.60  107 m   4.32  1019 J

7. red light : f  4.8  1014 Hz maximum E  hf 1    6.63  1034 J  s   4.8  1014  s   3.18  1029 J

This is less than the required photon energy, so no chemical reaction occurs in the paper.

8.

(a) f 

c 

m s  6.80  107 m 3.00  108



3.00  108 6.80  107 m

 4.41  1014 Hz

(b) This is in the frequency range of red light.

m 1  s m

9.

E  h

1 1  c  E1  E2  hc      1  2   m  1 1   6.63  1034 Js  3.00 108     7 7 s   3.00 10 m 5.60 10 m   Js m 1  6.63  1034  3.00  108  1.54  106   1 s m  3.06 1019 J







 

 



10. c  f 

f 

c 

m s  1.00  103m 3.00  108



3.00  108 1.00  103

m 1  s m



3.00  108 1.00  103

1 s

 3.00  1022 Hz

8

Atoms and Periodic Properties

Contents Atomic Structure Discovered Discovery of the Electron The Nucleus The Bohr Model The Quantum Concept Atomic Spectra Bohr's Theory Quantum Mechanics The Periodic Table Metals, Nonmetals, and Semiconductors

Overview As a fundamental unit of matter, the concept of the atom is foundational for learning science.

This chapter describes the structure of the atom through a historical perspective. Some of the quantitative aspects of electric and magnetic fields, electromagnetic energy, and mechanics are used by scientists such as Thomson, Millikan, Rutherford, and Bohr as they identify the parts of an atom and determine how the parts are organized through historic experiments. Thomson's discovery of the electron and Rutherford's discovery of the nucleus are discussed, along with Bohr's development of the planetary model of the atom. How Bohr's model accounted for atomic stability and its ability to produce line spectra is analyzed, along with the weaknesses and shortcomings of the model. The wave nature of particles as suggested by de Broglie is considered next, which leads to the modern quantum mechanics model. Overall, the symmetry found in nature should be emphasized as well as how scientific models are developed as they develop an understanding of atomic theory.

Symmetry is also found by organizing the experimentally discovered facts about atomic structure into the major concept represented by the periodic table. The periodic table

demonstrates the periodic recurrence of physical and chemical properties of elements. Elements within chemical families are seen to have similar chemical and physical properties because they all have the same number of electrons in their outermost shells. Across a period, elements are seen to have properties of metals with decreasing chemical activity, then properties of semiconductors, then properties of nonmetals with increasing reactivity, and finally the chemically inert noble gases. Metals are recognized as elements with one, two, and sometimes three electrons in the outermost orbital. Nonmetals have five, six, or seven outer orbital electrons. The inertness of the noble gases is related to the stability of the filled outer orbital arrangement. There are many generalizations that can be made from these periodic patterns, making the periodic table an invaluable tool that simplifies the study of matter.

Suggestions 1. The key idea here is that atoms are mostly empty space, yet they make up most of the matter tangibly familiar to students.

2. When equipment is readily available, actual demonstrations are preferable. Nonetheless, Internet-based videos are also useful. In any event, time should be allocated to show students phenomena repeatedly, as they will have limited exposure to these ideas. Illustrate the concepts of Thomson's experiment with Crookes tubes connected to a tesla coil if possible. Demonstrate that the cathode rays travel in straight lines with the Maltese cross, that they have mass and velocity with the kinetic energy effect tube. Demonstrate that cathode rays have a negative charge with the deflection effect tube, and that they can be deflected by a magnet. These demonstrations should lead to a clear understanding of Thomson's work and the properties of electrons.

3. Spectra of different elements can be shown by using several gas emission tubes and squares of inexpensive plastic replica diffraction gratings work well and if not available in the physics department, are often available in the chemistry store room. Have the students hold the plastic diffraction gratings by the edges (to keep finger oils off the plastic surfaces) and look through the grating at a glowing gas emission tube (H, Ne, Ar). They should rotate the grating and look to the right or to the left of the center until they see the spectrum. Energy emitted from excited atoms is also shown by the popular demonstration of crushing a wintergreen lifesaver between the jaws of a pair of pliers in a dark room. This emission of light is a result of the excitation of sugar molecules by mechanical stress.

4. Apparatuses for demonstrating the photoelectric effect, Thomson's experiment, and Millikan's experiment are available from scientific supply companies. The Millikan apparatus, however, does not lend itself to large-group demonstrations. It is also difficult to use with small groups.

Alpha tracks can be shown in a cloud chamber while discussing Rutherford's experiment.

5. Student understanding of the arrangement of electrons in atoms requires that they mentally act on the process of building electron structures as models. If you choose to cover quantum

numbers, it may be helpful to use an analogy to an address, such as state, city, street, and street number. Each electron has its own address (set of quantum numbers) just as each student has a particular address.

6. Illustrate metals and nonmetals with samples of gases in tubes; sheets of copper, zinc, lead, and aluminum; and samples of sulfur, carbon, and iodine. Show mixtures of salt and pepper, sand and dirt, or other common mixtures in varying proportions.

7. An electrolysis of water demonstration is an ideal way to begin discussion of compounds and elements. The Brownlee electrolysis apparatus, available from scientific supply houses, is big enough to be viewed by large classes.

8. Illustrate atomic mass units by using a balance to measure the mass of two coins, such as a dime and a quarter. Calculate the ratio of the mass of one coin relative to the other. Measure the mass of a bag containing equal numbers of both coins, then use the ratio to predict the numbers of each coin in the bag. Define atomic mass units and the abbreviation u.

9. Exhibit a large periodic chart of the elements, referring to the chart often during discussion of chemistry.

10. Illustrate similarities in chemical and physical properties of families and periods of the periodic table. Show the physical properties of Li, Na, and K, then show the chemical reactions with water (Caution: Explosive hydrogen gas), testing the water with litmus. Compare the reactions of Mg, Al, S, C, and Si with dilute hydrochloric acid. Review the main shell structures or electron dot symbols to show similarities among families and periods for the first twenty elements.

11. Do the classic demonstration showing the change of physical properties when a mixture of sulfur and iron is converted into a compound. First, demonstrate that a magnet will attract iron, but not sulfur, and a magnet can be used to separate iron from a mixture of iron and sulfur.

Second, demonstrate that sulfur is soluble in carbon disulfide (Caution: Explosive vapors) by dissolving a little in a one-fourth test tube of carbon disulfide. Finally, strongly heat a mixture of 4 grams S and 6 grams Fe filings in a test tube until it glows. Break the test tube by immersion in cold water. Compare the appearance and properties of the mixture before and after heating.

Discuss if it is still a mixture or a new compound according to the magnet and carbon disulfide tests.

12. Obtain a roll of calculator adding machine paper, typically 2 ¼‖ inches wide. Draw 100 squares on a length of the tape and write atomic numbers consecutively in the upper left corner of each square. In the center of each square write the chemical symbol for the atomic number.

Form a large spiral by taping together, one under the other, the elements of a family that have the similar chemical properties, such as the inert gases. You can hang the spiral in the classroom to make a mobile, then make another one to show how the periodic table is a spread-out spiral. Cut a spiral to the right of the inert gases, then spread and tape the spiral to make a long form of the periodic table. Show how moving two chemical families results in the short form.

For Class Discussions 1. In the modern view of the atom, an electron is most often found around the nucleus if a. it has no energy. b. it can make a standing wave. c. its momentum matches the electrical attraction from the nucleus. d. its wavelength describes an elliptical orbit.

2. Hydrogen, with its one electron, can produce a line spectrum with four visible colors because a. an isotope of hydrogen has four electrons. b. electrons occur naturally with four different colors. c. there are multiple energy levels that an electron can occupy. d. electrons are easily scattered.

3. A photon is emitted from the electronic structure of an atom when an electron a. jumps from a higher to a lower energy level. b. jumps from a lower to a lower higher level. c. reverses its spin by 180°. d. is removed from an atom by a high quantum of energy.

4. Quantum mechanics uses four quantum numbers to describe certain properties of electrons.

These properties do not include a. spin. b. what happens in a magnetic field. c. energy. d. mass.

5. According to the Bohr model of the atom, an electron is able to stay in orbit around an atom because of the a. balance between momentum and electrical attraction from the nucleus. b. balance between spin and orbital velocity, which gives the electron high stability. c. rule that electrons could not move from their allowed orbit. d. fact that moving electrons have mass and velocity, and therefore momentum.

6. The quantum mechanics and Bohr models of the atom both agree on a. the significance of the de Broglie wavelength and the circumference of an orbit. b. the importance of momentum in determining the size of an orbit. c. how electrons are able to emit light. d. none of the above.

7. The atomic weight of neon is 20.2. This means a. all atoms of neon have a mass of 20.2 u relative to carbon 12. b. a given atom of neon has a mass of 20.2 g. c. neon occurs as isotopes of different masses and the weighted average is 20.2 u.

8. An atom has 6 protons, 6 electrons, and 6 neutrons so the mass number is a. 18 12 Mg b. 12 12 Mg 12 c. 6 C d. 186 C 9. How many dots would surround the symbol for each alkali metal atom in the electron dot notation for the group IA elements? a. one. b. two. c. six. d. seven.

10. How many dots would surround the symbol for each halogen atom in the electron dot notation for the group VIIA elements? a. one. b. two. c. six. d. seven.

11. Calcium belongs to which chemical family? a. alkali metals b. alkaline earth metals c. halogens d. noble gases 12. The most important factor in the chemical behavior of an atom is the a. number of neutrons. b. structure of the isotopes. c. ratio of neutrons to protons. d. electron structure Answers: 1b, 2c, 3a, 4d, 5a, 6c, 7c, 8c, 9a, 10d, 11b, 12d.

Answers to End of Chapter Concept Questions 1. The cathode rays behaved like negatively charged particles when passing between plates, one of which was positively charged and one negatively charged. By using a combination of electric and magnetic fields, Thomson determined the ratio of charge to mass of the individual particles.

Since this ratio was the same, no matter what the conditions under which he measured the ratio, Thomson was convinced that a fundamental particle had been discovered.

2. Rutherford was scattering positively charged alpha particles off thin sheets of metal. Some of the particles were scattered at very large angles, and some particles were indeed scattered back toward the way they came. This behavior could be accounted for only by theorizing that the massive, positively charged alpha particles were being repelled by a massive positive charge concentrated in the center of the metal atoms. Rutherford concluded that the atoms must have a tiny, massive, positively charged nucleus surrounded by the negatively charged electrons.

3. The ―solar system‖ model requires electrons to travel in orbits about the positively charged nucleus and any object moving in a circle is accelerating. Since accelerating electrons emit energy in the form of waves, this loss of energy would result in the electrons spiraling in to collide with the nucleus. Since atoms are not observed to exhibit this behavior, this model is not wholly correct.

4. If the size of the nucleus was the same size as the thickness of a dime, the atom would be about two football fields wide.

5. The atomic number is the number of protons in the nucleus of an atom of an element. Since the number of protons in the nucleus determines which element the atom is, the atomic number is directly related to the element. If an atom is not ionized (is electrically neutral), the number of electrons must equal the number of protons or the atomic number.

6. The atomic number is 11. The element with an atomic number of 11 is sodium.

7. Atomic weight is a weighted average of the isotopes based on (1) their mass compared to carbon-12, and (2) their relative abundance in nature.

8. The three main points of the Bohr model are that the electrons can revolve around the atom only in specific allowed orbits, the electrons in these orbits do not radiate energy as long as the electrons remain in the orbit, and an electron gains or loses energy only by moving from one allowed orbit to another.

9. The reference level for the potential energy of an electron is zero when the electron is free and removed from an atom. Work must be done on electrons to remove them from an atom, bringing them back up to a potential energy level of zero, so the electrons in an atom have negative energy values.

10. The energy level of an electron is inversely proportional to the square of the energy level, which means that higher energy levels have lower values for their energy. Thus the lowest energy level is closest to the nucleus and the higher energy level is farthest from the nucleus.

Since these values are negative, however, the higher energy levels have higher energy (closer to a potential energy of zero).

11. The discrete energy levels, electrons gaining or losing energy by moving from one allowed energy level to another, and the emission and absorption of photons of energy exactly equal to the energy difference of the allowed energy levels are common to both models. Bohr's model was based on the solar system model, which gives exact radii for the electron orbits. It does not take into account the Heisenberg uncertainty principle as the probabilities contained in the quantum mechanical model do. The Bohr model treats electrons exclusively as particles, whereas the quantum mechanical model accounts for the dual nature of particles.

12. The electron associated with the hydrogen atom in the excited state has more energy than the electron associated with the atom in the ground state. Therefore, the atom in the excited state is said to have more energy than the atom in the ground state.

13. Answers will vary in this evaluation but will show understanding of Millikan‘s technique.

14. Similarities – isotopes of a particular element all have the same atomic number. Difference – isotopes of a particular element all have different numbers of neutrons in the nucleus, and thus different mass numbers.

15. This requires analyzing and evaluating an interpretation of Thompson‘s experiments. The correct analysis should include a discussion of electrons having mass as shown by response to magnetic field, electrons having a negative change, and the mass to charge ratio being the same for all materials.

16. This requires analyzing, exploring beliefs, and clarifying a conceptual understanding.

Answers will vary but should clarify that atomic weight is a weighted average of the isotopes of an element based on abundance and compared to carbon-12.

17. Answer should include discussion of photons, or quanta of energy that is emitted or absorbed.

18. The Bohr model considered the electron to be a particle and treated it as such with Newtonian mechanics using one quantum number. The Quantum Mechanic model considered the electron to be a wave and solved a wave equation for four quantum numbers that describe the energy of the electrons.

End of Chapter Group B Solutions 1.

From figure 8.11: n = 1 value is  2.18 1018 J and n = 3 value is  2.42 1019 J

 2.42 10 J    2.18 10 J   1.93 10 19

18

18

J

2. hf  EH  EL 

f   

EH  EL h  5.44  1019 J    2.18  1018 J  6.63  1034 J  s 1.64  1018 J 6.63  1034 J  s

1 s 15  2.48  10 Hz  2.48  1015

3.

E1 n2 13.6eV  22   3.40eV

E2 

4. mass  

charge charge / mass 1.60  1019 C C 9.58  107 kg

1.60  1019 C kg   9.58  107 1 C  1.67  1027 kg

9

Chemical Reactions

Contents Compounds Elements Chemical Change Valence Electrons and Ions Chemical Bonds Ionic Bonds Covalent Bonds Composition of Compounds Chemical Equations Types of Chemical Reactions Combination Reactions Decomposition Reactions Replacement Reactions Ion Exchange Reactions

Overview The core idea of chemistry is the combinations of atoms into molecules that make up our world is based in how electrons move between atoms. This chapter covers the concepts of chemical change, including elements and compounds, and chemical bonding (ionic and covalent) and the basic types of chemical reactions. The concepts of naming compounds, how to write formulas equations, and how to write and balance chemical equations are core to this chapter.

The periodic table is not meant to be memorized, rather to serve as a useful tool in determining how molecules are put together. It is helpful to begin by reviewing the valence electrons and ionic charges on the monatomic ions of elements in groups I, II, VI, and VII and then writing the ionic formulas. Students should realize that formulas can be easily written by knowing the ion name, symbol, and charge, which can be easily obtained by looking at the group number in the periodic table. Once this is understood, it becomes a matter of following the rules and understanding the basic generalization and models to write balanced chemical equations.

Suggestions 1. Illustrate the physical and chemical properties of powdered iron and sulfur before and after heating a mixture in a crucible with a burner to produce an obvious chemical change.

2. Have students make shell diagrams or electron dot symbols for various elements. Then ask them to explain how they could attain the more stable electron structures of the noble gas configurations by loss, gain, or sharing of electrons.

3. To illustrate combustion without the presence of oxygen, heat a piece of steel wool and plunge in into a bottle of chlorine (Caution: Rapid oxidation).

4. Show the polarity of water by deflecting a thin stream from a tap with both a negatively and a positively charged rod. A similar stream of a nonpolar compound, such as mineral oil, is not deflected by either charge.

5. Illustrate as many of the types of chemical reactions as possible with demonstrations, explaining the meaning of the generalized form of the reaction in each case. A strip of magnesium can be burned in air, for example, to illustrate a combination reaction. The generalized form of X + Y  XY should be described during the discussion.

6. Decomposition reactions can be illustrated by heating calcium carbonate or soda water, then testing for the production of carbon dioxide with limewater.

7. A variety of metal and salt solution replacement reactions can be demonstrated to illustrate replacement reactions, and the results can be used to establish a relative activity series of metals.

Include combinations of metals and salt solutions that result in ―no reaction‖ to help establish the activity series.

8. Ion exchange reactions can be illustrated by looking for the formation of a precipitate, a molecular substance, or a gas. Demonstrate several of these reactions before explaining what happened by way of equations.

9. Depending on the science experience and mathematical background of the students, it may be appropriate to illustrate the quantitative interpretations of the mole relationships in a chemical equation.

10. Additional demonstrations: (a) Do the spectacular demonstration of an ammonium dichromate volcano. Place an approximate 5 cm pile of ammonium dichromate on a metal tray. Ignite with a torch or burner flame (or short piece of burning magnesium ribbon). A large volume of green chromic oxide ―cinders‖ will form a conical pile. The burning reaction releases ammonia and oxygen, and the remaining chromic oxide has a weight of about 40 percent less than the original ammonium dichromate. (b) A 110-volt conductivity apparatus with electrodes about 1 cm apart can be used to show that molten NaCl conducts an electric current while solid NaCl does not. Attach the apparatus to a ring stand so the electrodes are in a 2-cm depth of granulated NaCl in a small porcelain crucible.

The crucible is in a triangle on a tripod. Show the lamp does not light when the switch is closed.

Now melt the NaCl with a Fisher burner under the crucible (requires 3 to 4 minutes), and again

close the switch on the conductivity apparatus. Allow the melt to cool and solidify until the lamp goes out. Explain that melted NaCl has mobile ions that can conduct a current. As the rigid lattice structure is established by ionic bonding, the ions are no longer free to move and conduct the current. (c) Burn a strip of Mg (Caution: Use tongs. Do not look directly at burning.) as an example of a combination reaction. (d) As an example of a decomposition reaction, mix concentrated H2SO4 in a small (50 mL or so) beaker half filled with table sugar. The sugar is decomposed to a growing ―tower‖ of carbon.

(Caution: Noxious fumes. Use fume hood or perform outside.) (e) As an example for a replacement reaction, place an iron file in copper(II) sulfate solution or Cu wire in silver nitrate solution. (f) As an example of an ion exchange reaction, mix a sodium chloride solution with a solution of silver nitrate. Check for insolubility of products: NaCl + AgNO3  NaNO3 + AgCl.

For Class Discussions 1. When involved in a chemical reaction with metals, atoms of a nonmetal tend to a. exchange electrons. b. remain neutral. c. gain electrons. d. lose electrons.

2. Potassium is a metal and oxygen is a nonmetal that react to form K2O, an ionic compound.

How many electrons were lost by an atom during the reaction? Each a. potassium atom lost one electron. b. potassium atom lost two electrons. c. oxygen atom lost one electron. d. oxygen atom lost two electrons.

3. A crystal of potassium chloride is made up of a. K and Cl atoms. b. KCl molecules. c. K+ and Cl– ions d. K– and Cl+ ions 4. In a covalent molecule you would find atoms that a. have lost electrons to become ions. b. have gained electrons to become ions. c. are sharing at least one pair of electrons. d. are sharing at least one electron.

5. The coefficients needed to balance the equation Na3PO4 + AgNO3  NaNO3 + Ag3PO4 are a. 1, 1, 1, 1 b. 3, 1, 1, 3 c. 2, 3, 3, 2 d. 1, 3, 3, 1 6. When hydrocarbons and carbohydrates burn with sufficient O2 they a. always give off CO2 and H2O. b. sometimes give off CO2, but never H2O. c. sometimes give off H2O, but never CO2. d. never give off CO2 or H2O. 7. How many atoms are in a molecule of chalk, which is CaCO3? a. 3 b. 5 c. 6 8. How many atoms of oxygen are in a molecule of Al2(CO3)3? a. 3 b. 6 c. 9 d. 14 9. If Iron(II) chromate has a formula of FeCrO4, then potassium chromate must have a formula of a. KCrO4 b. K2CrO4 c. K2(CrO4)2 d. K(CrO4)2 10. Should dihydrogen monoxide, which is responsible for substantial damage to the environment each year, be banned? a. Yes. b. No.

Answers: 1a, 2a, 3c, 4c, 5d, 6a, 7b, 8c, 9b, 10b (systematic name for water).

Answers to End of Chapter Concept Questions 1. A chemical change involves a change in the identity and properties of the substance, while a physical change is merely a size, shape, volume, or phase change. Three examples of a chemical change are wood burning, burning gasoline in a car engine, and iron rusting. Three examples of a physical change are ice melting, water boiling, and water condensing on the side of a water glass.

2. (a) A sodium atom and a sodium ion both have the same atomic number, and if the two are the same isotope, they have the same mass number. The atom and the ion will have different numbers of electrons, and consequently, different charges. (b) A sodium ion and a neon atom will have the same number of electrons, but they have different atomic numbers and different net charges.

3. In an ionic bond, one or more electrons are pulled from one atom to fill the outer shell of another atom. The resulting ions that are created are attracted to each other electrostatically. In a covalent bond, electrons are shared between the atoms, and the attraction of each nucleus for the other's electron binds the atoms together. The atoms involved in these two bond types both follow the octet rule. This is done either by sharing electrons to have eight in the outer shell as in a covalent bond or by losing or gaining electrons as in the ionic bond.

4. The octet rule states that atoms attempt to acquire an outer orbital with eight electrons. This rule is a generalization, and not all elements follow this rule.

5. Polyatomic ions are groups of two or more elements bound tightly together which behave much like a single monatomic ion. The hydroxide ion (formula OH) with a net charge of 1 and the cyanide ion (formula CN) with a net charge of 1 are examples.

6. The formula of magnesium hydroxide is Mg(OH)2. The parentheses indicate that the OH pair is a polyatomic ion that occurs twice in this compound.

7. A double bond is a covalent bond in which two pairs of electrons are shared. Similarly, in a triple bond three pairs of electrons are shared in the bond.

8. Conservation of mass states that matter is neither created nor destroyed in a chemical reaction.

A chemical equation conforms to this law only if each element appears the same number of times on each side of the equation.

9. Beginning with the unbalanced equation, the number of each kind of atom on each side of the equation must be counted. These numbers are used to determine whether to place coefficients in front of the formulas and what the coefficients should be. The equation should be checked to make sure that the number of each type of atom on each side is equal and that the coefficients are in the lowest whole number ratio.

10. An element higher on the table will replace an element lower on the table in an ionic compound. If the element in the ionic compound is higher on the table than the other element proposed to replace it, no reaction will occur.

11. The formation of a precipitate, a gas, or water must occur for an ion exchange reaction to take place. If this does not occur, no ions have been removed, so no reaction has taken place.

12. (a) The reaction for the combustion of ethyl alcohol is C2H5OH + 3 O2  2 CO2 + 3 H2O. (b) The reaction for the rusting of aluminum is 4 Al + 3 O2  2 Al2O3.

13. Similarities – both are recognizable changes in the physical state or chemical composition of matter. Difference – chemical change alters the identity of matter, producing a new substance with different properties; physical change does not alter the identity of matter.

14. You would know for sure that you have a compound and not an element if it is a pure substance that can be broken down into simpler substances by chemical change.

15. If a substance cannot be decomposed it might be an element or it might be a very stable compound. Extended testing might be necessary before you are sure that the substance is an element.

16. Metal atoms from the left side of the periodic table have a few electrons in outer orbitals that can be transferred to nonmetal atoms that are lacking a few electrons to fill the outer orbitals.

This sets up ionic bonding reactions as the octet rule is satisfied. Nonmetallic elements, on the other hand, can satisfy the octet rule by sharing electrons through covalent bonds.

17. Word equations describe a chemical change in general but say nothing about the quantities of the chemicals involved in the change. The advantage of writing a chemical equation with chemical symbols is that more information is provided about the composition of chemicals as well as the quantities involved. The disadvantage to this is that it requires knowledge and understanding of formulas as well as chemical symbols.

18. Answers will vary but will follow the generalized form of each reaction.

19. In sequence, (1) write the correct formulas for the reactants and products in a chemical equation. (2) Inventory the number of each kind of atom on each side of the equation. (3) Place coefficients in front of formulas to balance the equation. (4) Take another inventory to determine if the numbers of atoms on both sides are equal.

End of Chapter Group B Solutions 1.

(a) Na: 1

(d) I: 7

(b) P: 5

(e) Te: 6

(c) Br: 7

(f) Sr: 2

2. (a)

Al

(c)

Mg

(e)

C

(b)

F

(d)

Na

(f)

Cl

3.

4.

(a) Al: 3+

(d) Na: 1+

(b) Cl: 1¯

(e) S: 2¯

(c) Mg: 2+

(f) H: 1+

(a) acetate (b) hydrogen carbonate (c) sulfate

5. (a) Al(OH)3 (b) Na3PO4 (c) CuCl2

6. (a) SiO2

(d) nitrate (e) permanganate (f) carbonate

(d) (NH4)2SO4 (e) NaHCO3 (f) CoCl2

(d) H2O2

(b) H2S

(e) CF4

(c) BF3

(f) NH3

7. (a) Dinitrogen monoxide

(d) Phosphorous pentafluoride

(b) Sulfur dioxide

(e) Selenium hexachloride

(c) Silicon carbide

(f) Dinitrogen tetroxide

8.

(a)

2 NO + O2  2 NO2

(b) 2 KClO3  2 KCl + 3 O2 (c)

2 NH4Cl + Ca(OH)2  CaCl2 + 2 NH3 + 2 H2O

(d) 2 NaNO3 + H2SO4  Na2SO4 + 2 HNO3 (e) PbS + 4 H2O2  PbSO4 + 4 H2O (f)

Al2(SO4)3 + 3 BaCl2  2 AlCl3 + 3 BaSO4

9. (a) Decomposition (b) Replacement (c) Combination

(d) Ion exchange (e) Ion exchange (f) Replacement

(a) 2 C3H6(g) + 9 O2(g)  6 CO2(g) + 6 H2O(g)

10.

(b) H2SO4(aq) + 2 KOH(aq)  K2SO4(aq) + 2 H2O(l) (c)

C6H12O6(s) + 6 O2(g)  6 CO2(g) + 6 H2O(l)

(d) Na3PO4(aq) + 3 AgNO3(aq)  3 NaNO3(aq) + Ag3PO4(aq) (e)

3 NaOH(aq) + Al(NO3)3(aq)  3 NaNO3(aq) + Al(OH)3(aq)

(f) 3 Mg(OH)2(aq) + 2 H3PO4(aq)  Mg3(PO4)2(aq) + 6 H2O(l)

10

Water and Solutions

Contents Household Water

Properties of Water Structure of the Water Molecule The Dissolving Process Solubility Properties of Water Solutions Electrolytes Boiling Point Freezing Point Acids, Bases, and Salts Properties of Acids and Bases Explaining Acid-Base Properties Strong and Weak Acids and Bases The pH Scale Properties of Salts Hard and Soft Water

Overview Water is ubiquitous on our ocean-covered planet and is essential to life in every way we can think of. This chapter provides opportunities for the application of many fundamental chemical principles that were introduced in previous chapters. These principles are centered on solutions —what they are, how they are measured, and how they are used in many everyday activities.

This includes the concepts of solubility and insolubility, the physical properties of water, the dissolving process, the properties of acids, bases, and salts, the pH concept, and soft and hard water. The chapter materials can be presented at practically any depth to match the interest and abilities of the class. When couched in terms of environmental issues, student interest in the materials of this chapter can be encouraged because of the many apparent applications to and explanations of everyday activities.

Suggestions 1. A variety of everyday solutions that relate concentrations can be displayed, such as bleaches, vinegar, hydrogen peroxide, beverages, and so forth. Recent news articles that report concentrations of minerals or pollutants in water or in the atmosphere can be analyzed and compared to other concentrations to bring relevancy to the lesson.

2. The concept of a solution is illustrated by mixing 100 mL of absolute alcohol with 100 mL of water. The resulting solution has a volume less than 200 mL, which raises the question of what happened to the missing solution. Use 100 mL of salt mixed with 100 mL of B-Bs for a model to show how smaller particles can get between the spaces of the larger particles. This makes less total volume (a bushel of peas mixed with a bushel of potatoes does not make two bushels of peas and potatoes). Relate the model to the alcohol and water mixture.

3. Stir small amounts of a soluble salt, such as potassium nitrate, in water in ever increasing amounts. Have the class identify when the solution is dilute, when it is concentrated, and when it is saturated. Students soon understand the vagueness of the terms ―dilute‖ and ―concentrated,‖ opening the way for a discussion of different ways to express concentration measurements.

4. Demonstrate how much the boiling point is elevated by adding a pinch of salt to a liter of water. Then relate the findings to the habit of some cooks adding a pinch of salt to water when cooking. See how much salt you must add to cause a meaningful change in the boiling point.

Relate findings to text materials.

5. Test the electrical conductivity of various compounds and solutions with a flashlight bulb and battery. Complete the circuit by plunging the two ends of the exposed wires into pure acetic acid placed in a beaker. Then add water to produce ions and test again. Try the same arrangement with powdered sodium hydroxide, then add water and repeat.

6. If a pH meter is available, add equal amounts of hydrochloric acid and acetic acid to two beakers containing 100 mL of water. To give a color variation add several drops of universal indicator to each beaker. With the pH meter, check the pH of bleach and of vinegar. Pour the two substances together very slowly and check the pH to show neutrality. The amounts to produce neutrality should be determined in advance. Demonstrate the pH of distilled water and tap water.

7. Additional demonstrations: Set up the apparatus as illustrated in the following figure for the classic ammonia-fountain demonstration. The long glass tube has a tapered end that reaches about two-thirds of the way into a one-liter Florence flask. The medicine dropper contains a small amount of water. The beaker contains about 2-L water with about 6 drops of phenolphthalein. Charge the fountain by filling the Florence flask with relatively dry NH3. In a hood, use a gas generator with concentrated NH4OH dropped into solid NaOH pellets. Fill the Florence flask with the dry NH3 by downward displacement of air.

(Caution: Use a fume hood. Do not inhale ammonia.) Fit the stopper assembly into the flask, then invert over the beaker with phenolphthalein solution. Start the fountain by squeezing the water from the medicine dropper.

For Class Discussions 1. Substances that are ionic crystals are made up of a. isotopes. b. ions. c. atoms. d. molecules.

2. The intermolecular force of attraction known as a hydrogen bond comes from a. uneven distribution of charges around a molecule. b. electrons being transferred from one molecule to another. c. the symmetry of even charge distribution in a molecule. d. electrons being shared and re-shared in a symmetrical molecule.

3. A solution with a pH of 7 is a. slightly acidic. b. slightly basic. c. neutral.

4. Water is able to dissolve certain ionic compounds because water is made up of a. separated positive and negative ions. b. symmetrical covalent molecules. c. strongly polar molecules. d. slightly acidic molecules.

5. Suppose it is late during a very cold winter and there is a very deep lake that has a thick layer of ice on top. The temperature of the water at the bottom of this lake should be a. 0°C b. 4°C c. 10°C d. unknown 6. Adding a solute, such as salt, will have what effect on the freezing point of water? It a. is lowered. b. is raised. c. remains the same.

7. A strong acid is strong because it is a. completely ionized in water. b. free of dissolved materials. c. mostly insoluble in water. d. made up of nonpolar molecules.

8. Will a solute that raises the boiling point of water also raise the freezing point? a. Yes. b. No.

Answers: 1b, 2a, 3c, 4c, 5b, 6a, 7a, 8b.

Answers to End of Chapter Concept Questions 1. A solution is a homogeneous mixture of ions or molecules of two or more substances. Not all mixtures are homogeneous and not all are mixtures of ions or molecules.

2. If the attraction between the ions is greater than the hydration energy the ionic compound is insoluble in water. Ionic compounds whose attraction to the polarized water molecules is greater than those between ions are soluble.

3. The presence of the dissolved salt decreases the number of water molecules at the surface.

This occurs since the sodium ions and chlorine ions are taking up some of the space near the surface. Since there are fewer water molecules near the surface to escape, the vapor pressure is lowered. This increases the temperature necessary to obtain the vapor pressure required to boil the water and salt solution.

4. The greatest density of water occurs at a temperature of 4˚ C. A lake covered with ice (0˚ C) would probably have the greatest density water—with a temperature of 4˚ C—at the bottom of the lake.

5. Water at very close to freezing has hydrogen bonds present between many of the molecules.

These bonds spread out the water molecules. As the temperature of the water increases above the freezing point (from 0˚ to 4˚ C), the bonds break and allow the molecules to collapse together.

6. A solution of Ca2+ or Mg2+ ions in water is called hard water. Removing the calcium and magnesium ions softens the water.

7. NaCl does not donate protons to form hydronium ions, and it does not accept protons to form hydroxide ions when it is dissolved in water. Since the pH scale is a measure of the hydronium ion concentration, the pH does not change because the hydronium ion concentration does not change.

8. A hydrogen bond is a weak to moderate strength bond between the hydrogen end (+) of a polar molecule and the negative end () of a second polar molecule. The bond forms when the positively charged end of a polar molecule, which is usually a hydrogen atom, is attracted to the negative end of another polar molecule. This negative end is usually an oxygen, fluorine, or nitrogen atom. If the two ends come close enough together, this electrical force of attraction forms a bond.

9. A soap molecule has two parts, a part that is polar, which allows the soap to be soluble in water, and a nonpolar part, which is absorbed into oil. Soap molecules attach onto oil molecules and carry the oil away with rinse water.

10. (a) Acids are associated with the presence of hydronium ions in a water solution. (b) Bases are associated with the presence of hydroxide ions in a water solution.

11. Possible explanations should involve a discussion of water as a polar molecule and hydrogen bonding.

12. A salt that will dissolve does so because the attraction between the polar water molecules and a charged ion is greater than the attraction between the ions. A salt that will not dissolve has greater attractions between the ions than between the polar water molecules and the ions.

13. The boiling point is defined as occurring in pure water at sea level pressure.

14. Similarities – Acids and bases are chemical opposites dissolved in water and a salt is produced by a neutralization reaction between and acid and a base. Differences – An acid is a proton donor in a water solution; a base is a proton acceptor in a water solution; a salt is an ionic compound produced when acids and bases react.

15. Answers will vary but should include the basic idea that pH is a power of ten notation that expresses the hydronium ion concentration. The scale ranges from 1 (most acidic) to 14 (most basic), with 7.0 as the pH of a neutral solution.

16. Answers will vary but should include the basic idea that a solution of Ca2+ or Mg2+ ions in water is called hard water, and removing these ions will soften the water.

End of Chapter Group B Solutions 1.

ρ

m V

 V

m 1.000 g   1.0003 cm3 ρ 0.99973 g cm3

2. If room temperature is about 20C, then following the solubility line on figure 10.6, the solubility of NaNO3 is about 90 g of solute per 100 g of water.

3. According to the graph in figure 10.6, the solubility of NaCl does not change appreciably as temperature is increased.

4.

100.261 C  100C = 0.261C 0.261 C 

11

29.2 g  14.6 g 0.521 C

Nuclear Reactions

Contents Natural Radioactivity Nuclear Equations The Nature of the Nucleus Types of Radioactive Decay Radioactive Decay Series Measurement of Radiation

Measurement Methods Radiation Units Radiation Exposure Nuclear Energy Nuclear Fission Nuclear Power Plants Nuclear Fusion

Overview Radioactivity is a word that sometimes elicits fear in people because of its vague association with health risks and nuclear warfare. The purpose of this chapter is to develop a more accurate understanding of radioactivity and the issues involved in its uses in health fields and, in bulk, in electrical power generation. The bottom line is to move students to understand the advantages and disadvantages of radioactivity by first understanding what radioactivity is as an energy source.

As often happens in science, many great discoveries in this area were the result of seemingly unimportant incidents. The accidental exposure of photographic film to a uranium ore led to Becquerel‘s discovery of radioactivity. His continued research, along with that of Rutherford and the Curies, opened a new frontier for scientists of all specialties to explore.

The nature of the nucleus, the types of radioactive decay, the resulting radioactivity emitted, and the methods of measuring radiation set the stage for the discussion of the uses of nuclear energy. Few students know the identity of alpha and beta particles nor do they understand their origins. The similarities of electromagnetic energy of gamma rays, X-rays, radio waves, visible light, and so forth should be discussed, but being careful to distinguish this energy emission from particle-based radioactivity. Only energy and origin separate one from the other since the electromagnetic spectrum is continuous. The binding energy and mass defect are meaningful applications of the relationship of matter to energy, E = mc2. It is generally a surprise for students to learn that it is a physical impossibility for a nuclear power plant to explode as a nuclear bomb. Once this is understood, it is natural then to discuss the consequences of exposure to radioactivity and the controversy surrounding this topic. Finally, the concerns about nuclear wastes are explored.

The most common misconception generated by learning this chapter is related to the concept of half-life. Students naturally and mistakenly equate radioactive decay with the words disintegrate and evaporate. Special attention needs to be given to students to help them understand that when a substance undergoes radioactive decay, it does not disappear; rather, it turns into something else.

Suggestions

1. Misconceptions about radioactivity are common, and well poised to interfere with instruction.

Explicit instruction related to confronting radioactivity misconceptions is suggested.

2. Hospitals may release to you various X-ray photographs that might prove of interest to students. The negatives can be projected with an overhead projector.

3. Most states have a department of disaster or emergency services that have a supply of portable GM counters and other survey meters. You may find that these units are already available within the school, and they are excellent for demonstrations. Check with your institution’s radiation safety officer or a nearby health physicist to gain more local information.

4.Alpha particles can be detected with certain GM counters, for example, Pancake GM Tube Survey Meter Model #3 from Ludlum Measurements, Inc., Sweetwater TX. Other tubes are also available that can detect the alpha particle with some efficiency.

5. A portable GM counter, along with beta and gamma sources, is most useful in illustrating the properties of the two particles, including their activity, energy, and charge. The counter can also be used to check rocks, watches, pottery, dinnerware, and other substances for radioactivity. The lantern mantle used in unleaded gasoline and propane lanterns contains thorium oxide and provides an excellent source of radioactivity for demonstrations and laboratory measurements.

6. Additional demonstrations: (a) A cloud chamber can be used to show the tracks produced by emissions from radioactive materials. (b) A Geiger-Muller tube and counter can be used to show background radiation and test everyday materials for radioactivity. Test old, orange-colored pottery since uranium salts were formerly used as a color pigment. (c) Place a metal key on high speed photographic film, then cover the key and film with cutup lantern mantles. Develop the film in about a week or so. The black area around the white key image is a result of exposure to radiation. The lantern mantle contains radioactive thorium oxide.

For Class Discussions 1. The property of radioactivity in materials is caused by a. the pull of electrons on and the repulsion of protons in the nucleus. b. instability from struggles between electromagnetic and nuclear forces. c. nuclear instability from an accumulation of isotopes. d. nuclear forces, which squeeze particles out of the nucleus.

2. Radiation from a radioactive material can be any of the following except a. a helium nucleus. b. an electron. c. a proton. d. a gamma ray.

3. A beta particle, sometimes called a beta ray, is a. an electron from the nucleus. b. a photon from the nucleus. c. a proton from the nucleus. d. a photon from the second energy level.

4. Which of the following is most likely to happen to an alpha particle after it is emitted? a. It escapes to space, where it is known as a cosmic ray. b. After being absorbed by matter it is dissipated as radiant energy. c. After joining with subatomic particles it finds itself in a child's balloon. d. It joins others of its kind to make lightning and thunder.

5. Which of the following is most likely to happen to a beta particle after it is emitted? a. It escapes to space, where it is known as a cosmic ray. b. After being absorbed by matter it is dissipated as radiant energy. c. After joining with subatomic particles it finds itself in a child's balloon. d. It joins others of its kind to make lightning and thunder.

6. A nucleus emits a beta particle so the number of nucleons it contains is now a. more. b. less. c. the same.

7. A nucleus emits an alpha particle so the number of nucleons it contains is now a. more. b. less. c. the same.

8. The mass of an atomic nucleus compared to the mass of the individual nucleons making up the nucleus is always a. less b. more c. the same.

9. Enriched uranium has more a. energy. b. radioactivity. c. deuterium d. uranium-235.

10. The maximum binding energy per nucleon occurs in nuclei of a. low mass number. b. high mass number. c. intermediate mass number Answers: 1b, 2c, 3a, 4c, 5d, 6c, 7b, 8a, 9d, 10c.

Answers to End of Chapter Concept Questions 1. Radioactive materials emit invisible radiation. A radioactive material contains atoms that spontaneously emit particles or energy from their nuclei. This often results in the change of identity of these atoms, so radioactive materials often decompose into different materials.

Nonradioactive materials exhibit none of this behavior.

2. Radioactive decay is the natural spontaneous disintegration or decomposition of a nucleus.

Changing the decay rate is not possible.

3. The three kinds of radiation emitted by radioactive materials are as follows: alpha particles, which are helium nuclei; beta particles, which are electrons ejected at high speed; and gamma

radiation, which is a high-energy burst of electromagnetic radiation. Alpha particles eventually acquire electrons and become ordinary helium atoms. Beta particles either remain free electrons or join an ion to become part of an atom. Gamma radiation is absorbed by materials, giving its energy to the material absorbing it.

4. The force known as the strong nuclear force binds protons and neutrons together in a nucleus.

This force, over very short distances, is much stronger than the electromagnetic force and overcomes it.

5. A half-life is the time it takes half of the unstable nuclei in a radioactive substance to undergo radioactive decay and turn into something else. Iodine 131 has a half-life of eight days; after forty days, five half-lives have elapsed, and only 1/32 of the original material remains.

6. Isotopes with a longer half-life are less active than isotopes with shorter half-lives because the activity rate determines the half-life of a material. High activity gives short half-lives and more radioactivity.

7. Background radiation is radiation from natural sources that are part of the environment. The normal dose of background radiation is between 100 and 500 millirem per year.

8. Lack of knowledge, as well as the difficulty in obtaining reliable results not due to extraneous factors, fuels the controversy over long-term, low-level radiation exposure. Since cancer can arise from many factors, including a combination of seemingly unrelated actors, it is difficult to say that low-level radiation is responsible for any increased incidence of cancer.

9. The difference between the actual mass of a nucleus and the sum of the masses of individual nucleons making up the nucleus is the mass defect of the nucleus. This difference in mass has been converted to energy, which was released as the more stable nucleus was formed. This energy is equivalent to the binding energy of the nucleus, and it can be calculated by using the mass defect as the mass in Einstein's equation E = mc2.

10. Nuclear fusion is the process in which two nuclei with low mass numbers collide at very high speeds and ―stick together‖ to form a heavier, more stable nucleus. Nuclear fission is the nuclear reaction of splitting a massive nucleus into more stable, less massive nuclei. Both processes release energy because in both cases more stable nuclei are the result. More stable nuclei have larger binding energies, so energy must be released by less stable nuclei to gain stability.

11. A radioactive isotope has an unstable nucleus that will disintegrate into a simpler nucleus, giving off alpha, beta, or gamma radiation. An isotope that is not radioactive has a stable nucleus that will not disintegrate.

12. All types of radioactive decay are ionizing radiation, and this ionization can produce free polyatomic ions that can interfere with cell functions or disrupt chemical bonds in essential organic molecules such as DNA. 13. Answers will vary but address that some nuclear arrangements are less stable than others are.

14. Answers will vary but should illustrate the basic differences between the two models.

15. Figure 11.10 shows that the maximum binding energy per nucleon occurs around mass number 56, and then decreases in both directions. As a result, fission of massive nuclei and fusion of less massive nuclei both release energy.

16. Answers will vary but should point out that waste fuel rods contain an appreciable amount of usable uranium and plutonium.

17. Similarities – both supply energy through nuclear reactions. Differences – a fission power plant slowly provides energy through fission processes; a fusion power plant provides much energy through fusion processes; a fission reaction can be contained in a nuclear reactor, but a fusion reaction requires confining a hot plasma in a magnetic field.

End of Chapter Group B Solutions 1. (a) Al: 13 protons; 12 neutrons

(c) Sn: 50 protons; 70 neutrons

(b) Tc: 43 protons; 52 neutrons

(d) Hg: 80 protons; 120 neutrons

2. (a)

25 12

(c) 120 50 Sn

Al

(b) 9543Tc

(d) 200 80 Hg

3. (a) Unstable, because isotopes with an atomic number less than 83 are stable when the ratio of protons to neutrons in the nucleus is 1:1, which is not the case here. (b) There are odd numbers of both protons and neutrons, and the ratio of protons to neutrons is not 1:1, therefore it is unstable. (c) Stable, because there are even numbers of protons and neutrons. In addition, 50 is a particularly stable number of nucleons. (d) Stable, because there are even numbers of protons and neutrons, allowing them to pair up.

4.

(a) 146 C  147 N  01 e 60 0 (b) 60 26 Co  28 Ni  1 e

24 0 (c) 24 11 Na  12 Mg  1 e 241 0 (d) 241 94 Pu  95 Am  1 e 131 0 (e) 131 53 I  54 Xe  1 e

210 0 (f) 210 82 Pb  83 Bi  1 e

5.

4 Am  237 93 Np  2 He

(a)

241 95

(b)

232 90

(c)

223 88

4 Ra  219 86 Rn  2 He

(d)

243 92

U  23990Th  42 He

(e)

242 96

4 Cm  238 94 Pu  2 He

(f)

237 93

4 Np  233 91 Pa  2 He

4 Th  238 88 Ra  2 He

6. The fraction remaining is

1g 1g 1   or 3 1 kg 1  10 g 1,000

1 1 to equal or 2 n  1,000; 210  1,024, therefore n 2 1,000 ten half-lives have passed, for a total time of 10  30 years, or 300 years.

We wish

7. First, the mass difference needs to be calculated: before the reaction: 7.01435 u after the reaction: 3(1.00728 u) + 4(1.00867 u) = 7.05652 u mass difference: 7.05652 u - 7.01435 u = 0.04217 u 1u 

1.0  103 kg 1.0  103 kg  1 atom = 6.02  1023 atoms 6.02  1023 u

1.0  103 kg 0.04217 u   7.0  1029 kg 23 6.02  10 u E = mc 2 m    7.0  1029 kg   3.00  108  s   6.3  1022 J

12

The Universe

Contents The Night Sky Origin of Stars Brightness of Stars Star Temperature Star Types The Life of a Star Galaxies and the Universe The Milky Way Galaxy Other Galaxies

Overview Whereas in years past, many students have spent time gazing at clouds and wondering about stars, in recent years, fewer and fewer students have had these outside experiences. It is estimated that less than 25% of students have seen the Milky Way stretching up overhead on a dark night. For many students, they will be surprised to learn—after explicit instruction—that our Sun is a star—much like other stars in the night sky. You should point out that we know as much about stars as we do because we have a star, our Sun, relatively nearby to study. We are able to make photographs and measurements and obtain instrument readings of the Sun by telescopic observations and flyby space probes. The position of our star in the Hertzsprung-Russell diagram will help students realize that our Sun is but an average star in terms of size, surface temperature, and luminosity. The section on the life of a star can be made more personal to students by discussing the birth, evolution, and death of our Sun and the consequences of these events on Earth.

Our galaxy, with its hundreds of billions of stars, also contains many immense patches of gas and dust particles known as nebulas. All nebulas are essentially alike, but bright nebulas are bright because they are close to hot, bright stars, so the nebulas shine by reflections and fluorescence. Dark nebulas are so far from hot, bright stars that they appear dark. Most nebulas have been formed from the debris of exploding stars. New stars are still forming in the regions of many nebulas. This chapter also discusses our galaxy, the Milky Way

Suggestions 1. Compare life among the ancients with our lives today. Why might they have noticed more about the night skies than we do?

2. Point out the ancients‘ needs for accurate information about the positions of the stars, the Moon, and the Sun compared to our needs for such information.

3. You might have available crude models of the simple instruments the ancients used to make accurate measurements of the positions of the Sun, the stars, and other astronomical objects. To illustrate stellar parallax, draw a spot on the board. Have the students close one eye, hold a finger of an extended arm on the spot, and move their heads in a circular motion to simulate the revolution of Earth about the Sun. 4. Have an art major illustrate his or her interpretation of the birth of stars. Others may give their renditions of the various star classifications.

5. Pulsars can be related to the flashing lights of lighthouses, ambulances, or police vehicles.

Recordings of sounds made by various pulsars can be obtained from radio-telescope observations.

6. Plastic balls of various sizes and colors can be prepared to represent the different classifications of stars. The sequence involved in the life of a star can be illustrated very vividly with the models.

7. Have students observe the Milky Way if you are in a location where it can be seen at night.

Point out that they will be looking along the long axis of our galaxy.

8. Have students determine the length of a light year and then the dimensions of our galaxy in miles and kilometers.

9. The big bang theory of the expanding universe is well illustrated by a balloon with spots painted on it. An ant on the balloon's surface would see all spots recede as the balloon expands.

For Class Discussions 1. The radius of Earth's orbit around the Sun is a. a pair of seconds. b. a light year. c. an astronomical unit. d. an arc second.

2. More massive stars generate a. higher temperatures. b. lower temperatures. c. average temperatures. d. temperatures that are neither higher nor lower than less massive stars.

3. More massive stars on the main sequence tend to be a. brighter and bluish. b. white, with an average brightness. c. yellow, with an average brightness. d. fainter, with an reddish color.

4. Where a star is on the main sequence and what happens to it next depends on its a. composition. b. radius. c. temperature. d. mass.

5. Comparing the following list of star types, the oldest star is probably a(n) a. main sequence star. b. red giant. c. white dwarf.

6. Only a more massive main sequence star will have an opportunity to become a(n) a. white dwarf. b. supernova. c. red giant.

7. The star known as the Cepheid variable is important because they a. are very bright and easily identified. b. can be used as cosmic distance mileposts. c. help determine where a main sequence star is in the H-R diagram. d. serve as lighthouses, warning of cosmic hazards.

8. Our Milky Wag galaxy a. is about 33,000 light years across. b. has a radius of approximately 1 or 2 light years. c. contains about 95% of all the know stars in the universe. d. has a diameter of about 100,000 light years 9. According to the accepted model of the life cycle of a star, our Sun will next become a a. red giant b. white dwarf c. supernova d. black hole 10. A black hole might form when a. a white dwarf cools, no longer emitting light. b. the core of a super-massive star collapses. c. a neutron star begins to spin, creating an extremely powerful magnetic field. d. a supernova implodes.

Answers: 1c, 2a, 3a, 4d, 5c, 6b, 7b, 8d, 9a, 10b.

Answers to End of Chapter Concept Questions 1. A light year is a unit of distance defined as the distance light travels during one year. This distance is about 9.5  1012 km.

2. Astronomical distances are so large that measuring them in units of miles or kilometers would result in huge numbers. In addition, the large distances cause the standard units of length to have little meaning because there are no referent points of comparison. So light-years are used to measure distances in terms of time, and parsecs measure distances in terms of angles.

3. As the gas forming the protostar falls together, the gravitational potential energy of the gas is decreased. This energy is converted first to kinetic energy of the gas molecules. This kinetic energy is then converted to heat when the gas molecules collide as the gases grow denser.

4. Located at the center of a star and extending about one quarter of the distance to the surface of the star is the core. This region contains about half the mass of the star at a density of about twelve times that of solid lead and at a pressure of about 300 billion atmospheres. The temperature is about 15 million degrees Celsius. Above the core extending to about nine-tenths the way to the surface is the radiation zone. It has about the density of water and absorbs and reradiates energy from the core. The convection zone is in the final tenth of the way to the star‘s surface and is not very dense—only about 1 percent the density of water. Gases at the boundary between this zone and the radiation zone are heated, rise to the surface, and radiate away the energy that was originally released in the core of the star. The cooler gases then contract and fall to begin the process again. The temperature at the surface is about 5500°C. 5. The more massive a star, the higher the pressure at the core, and the faster the fusion reactions take place. Therefore, in general, even though more massive stars have more fuel, they use it at such a rapid rate that the massive stars ―burn out‖ more quickly than less massive stars. A star that has a mass of one twenty-fifth that of the Sun would last longer than both the Sun and a star sixty times as massive as the Sun. 6. Apparent magnitude is a measure of how bright a star appears in the sky. Since different stars of the same size might be at different distances from Earth, they might have different apparent magnitudes. To be able to compare the brightness of stars to one another directly, the absolute magnitude scale is used. This scale gives the brightness of a star if it were located 10 parsecs away from Earth.

7. The color and temperature of an incandescent object have long been understood to be closely related. This relationship is due to the electrons surrounding an atom being excited by higher temperatures to higher energy levels. When the electrons return to the ground state energy level, they emit light. The more energy that the electron has to lose to return to the ground state, the higher energy light it has to emit. Higher energy light is shorter frequency light, or ―bluer‖ light.

So hotter objects glow closer to the blue end of the spectrum and cooler objects emit light that is closer to the red end of the spectrum. Comparing the intensities of blue light and red light emitted by a star gives a good measure of the temperature. The spectral classification scheme is based upon the temperature of the star. Originally it was based upon the intensities of the

hydrogen lines in the star‘s spectra. The current system has a set of temperature ranges assigned to each classification. Type O is 30,000 to 80,000 K and is bluish. These stars are short-lived.

Type B is 10,000 to 30,000 K and again is bluish. The range of 7,500 to 10,000 K is type A, which is still bluish. The white type F has a range of 6,000 to 7,500 K, and the yellow stars like our type G Sun has a temperature of 5,000 to 6,000 K. The relatively cool type K stars are 3,500 to 5,000 K and are orange-red in color. The type M stars have a temperature of 2,000 to 3,500 K and are reddish.

8. The Hertzsprung-Russell diagram is a plot of the temperatures of stars indicated by spectral type versus the brightness of the stars indicated by absolute magnitude. The diagram shows that most stars fall close to a narrow diagonal band called the main sequence. The position of a star on this diagram suggests the star‘s mass and age.

9. The main sequence on the H-R diagram is the narrow diagonal band that runs from the bright blue stars down to the dimmer red stars. Most stars fall on or near this diagonal band. The mass of a main sequence star is the prime factor in determining if a star is hot and blue, cooler and yellow, or cold and red.

10. A star begins as a large cloud of gas that is gradually attracted together by gravity into a protostar. The protostar collapses down until the temperature and pressure at the center become high enough to sustain nuclear fusion. This fusion heats the core even more and the pressure at the core increases. Eventually equilibrium between the outward force of the pressure and the inward force of gravity is established after about fifty million years. The star is now a part of the main sequence and burns its fuel steadily. Eventually, the hydrogen in the center of the star begins to run out. The fusion reaction slows down and the equilibrium between the pressure and gravity is upset. The star again begins to collapse until the hydrogen remaining outside the core begins to fuse. This causes the outer layers of the star to expand, and the star becomes a red giant.

The star is no longer on the main sequence because its properties have changed. The helium core is heated by the fusing hydrogen surrounding it and eventually, after its temperature has risen enough, begins to fuse as well. The star moves back toward the main sequence when this stage is reached. After millions of years of helium fusion in the core and hydrogen fusion in the outer layers, the star heats up and again expands to a red giant. After this expansion, the center may cool enough so that the atoms in the core become neutral rather than part of an ionized plasma.

These neutral atoms absorb heat from the surrounding star and the star expands and cools. As it cools it begins to collapse back, heating the star again. This occurs several times and eventually blows the outer layers of the star away, forming a planetary nebula. The carbon core and helium fusion layer surrounding it gravitationally collapses to form a white dwarf.

11. A violent flare up increasing the brightness of a star for a short time is called a nova. Many novas occur because they are part of a binary star system. An old white dwarf star can gravitationally pull matter off a younger companion star until enough matter builds up on the surface of the white dwarf for a fusion explosion to ignite. A supernova is the rebound explosion from the catastrophic collapse of a massive star that has run out of fuel. The collapse is caused

by the loss of the supporting pressure from the fusion in the interior of the star as the fuel runs out.

12. (a) A white dwarf is formed if the star is about the mass of the Sun or less. The low mass of the star allows its center to convert from hot plasma to neutral matter. This absorbs heat from the surrounding star until the surrounding material undergoes an expansion-cooling and contractionheating process. Eventually the matter surrounding the core is blown away in a violent explosion. (b) A red giant star forms as the hydrogen in the core runs out and the star begins to collapse. When the hydrogen in the outer layers gets hot enough to fuse, the star expands to a red giant. A star can become a red giant twice in its life if helium in the core begins to fuse after it collapses from its initial red giant stage. The heat from this new energy source again expands the star. (c) When a giant star has used up all of its energy sources in the core and the outgoing pressure can no longer support its immense weight, it collapses in a catastrophic explosion called a supernova. If the remains of the compressed core after the supernova are between about 1.4 and 3 solar masses, the remaining matter is compressed so much that the nuclei of all the atoms collapse, forcing protons and electrons together into neutrons and forming the core of a small, super-dense neutron star. Such a neutron star has a center core of pure neutrons. (d) A black hole is the final stage of a supermassive star (with a mass greater than 3 solar masses) when all the fuel in the center has been used up. The core undergoes a gravitational collapse that has nothing to stop it. The force of gravity overwhelms all other forces and even prevents light from escaping. (e) A supernova is the result of the collapse of a star more massive than the Sun when all its fuel has been exhausted. The energy released in this collapse causes the outer layers of material to rebound outward in a violent explosion.

13. The pressure from the high temperatures at the center of a star trying to expand the core balances the force of gravity attempting to collapse the star. This equilibrium can last millions of years because the pressure is a result of the high temperatures from the fusion process. Since there is so much matter in a star, it takes millions of years to fuse together.

14. Massive stars can fuse elements to create heavier elements up to iron. If the stars are sufficiently massive to undergo a supernova, the energy released in the supernova explosion can fuse atoms to make even heavier elements.

15. Helium nuclei are more massive than hydrogen nuclei, and therefore when traveling at the same speed as hydrogen atoms they have a higher kinetic energy. Since temperature is a measure of the energy of the atoms, the temperature is higher. In addition, a helium nucleus has a higher positive charge than a hydrogen nucleus. This higher positive charge creates a larger repulsive force between helium nuclei than hydrogen nuclei, requiring even higher speeds for the nuclei to collide and fuse. These higher speeds mean higher kinetic energies of the atoms, which mean higher temperatures.

16. A protostar becomes a star when the fusion process is running stably in the core.

17. A red giant star is a bright, low-temperature star that is very large. A red giant star forms as the hydrogen in the core runs out and the star begins to collapse. When the hydrogen in the outer layers gets hot enough to fuse, the star expands to a red giant. A star can become a red giant twice in its life if helium in the core begins to fuse after it collapses from its initial red giant stage. The heat from this new energy source again expands the star. A red giant can be brighter than it was as a main sequence star because even though it has a lower surface temperature and is not as luminous, it has much more surface area radiating light, making the star very bright.

18. Since there is not enough mass to create the high pressures and temperatures required to fuse the heavier elements, the fusion process stops at helium fusion.

19. The expansion of the universe is the expansion of space itself. The galaxies are not growing larger, they are moving with space as it expands.

20. The big bang theory is supported by the presence of present-day microwave background radiation from outer space, the dispersive movement of galaxies, and the observed chemical makeup of the observable universe.

21. If this year is 2012, light leaving the star 520 years ago would have left in 1492 which is about when ―Columbus sailed the ocean blue.‖ 22. In general, a massive star is brighter, hotter, and has shorter a live than average-sized stars such as the Sun. This means the massive star will go through the various stages of its life in a shorter period.

23. Answers will vary but should include the understanding that absolute magnitude compensates for distance, while apparent magnitude represents what you see.

24. The Hertzsprung-Russell diagram is a temperature-brightness graph that shows groups of stars. These groups represent stars in various stages of their lives.

25. Answers will vary but should focus on spinning objects tend to flatten.

End of Chapter Group B Solutions 1. 1 ly  9.5  1012 km and d SiriusA  8.6 ly then 8.6 ly 

9.15  1012 km  8.2  1013 km 1 ly

2. mPolaris= +2.1 and mVega= +0.1 ; so magnitude difference = mPolaris  mVega =2.1 – 0.1 =2 magnitudes Bchange = (2.51) × (2.51) = 6.3 times brighter

3. mSpica= +1.2 and mVega = +0.1 ; so magnitude difference = mSpica - mVega = 1.2 – 0.1  1 magnitude Bchange = 2.51 = 2.51 times brighter 4. Time  1/M2.5 = 1/3M2.5 = 0.6 solar lifetimes 5. 1M=1 × 1057 atoms/star and nebula=1000 atoms/cm3 0.5 (1 × 1057 atoms/star) × 1/(4.19 × 1057 cm3) × 1 cm3/1000 atoms = 1193 stars of 0.5M 6. According to Table 12.2, blue stars have temperatures from 7,500 K and up 7. T = 2.897 × 107 K angstroms / λpeak = 2.897 × 107 K angstroms / 4570 angstroms = 6,339 K 8. T = 2.897 × 107 K angstroms / λpeak = 2.897 × 107 K angstroms / 8900 angstroms = 7,865 K According to Table 12.2, stars with temperature 7,865 K are blue Type A stars 9. λpeak = 2.897 × 107 K angstroms / temperature = 2.897 × 107 K angstroms / 9200 K = 3149 Å 10. 4.2 × 1012 km in 1995 and 5.0 × 1013 km in 2003 over 8 years (5.0 × 1013 km – 4.2 × 1012 km ) / 8 years = 5.7 × 1012 km/yr 11. v  H 0 d and H 0  v

20 km

Mly

s and d  10 Mly

s  10 Mly

Mly v  200 km

13

20 km

s

The Solar System

Contents Planets, Moons, and Other Bodies Mercury Venus Earth‘s Moon Mars Jupiter Saturn Uranus and Neptune Small Bodies of the Solar System Comets Asteroids Meteors and Meteorites Origin of the Solar System Stage A Stage B Stage C

Overview You might find fruitful the organizing structure of ―zooming down‖ to the solar system as if aboard a galactic visitor's spaceship. By asking students what a galactic visitor would see upon approaching our solar system, you can discuss the relative dimension of the system, the counterclockwise movement of the planets around the Sun as viewed from the direction of the North Star, and the relative sizes of the planets.

The dominant model about the origin of the solar system are discussed in the text in some detail, which leads naturally to the consideration of the planets as divided into two groups. The inner, or earthlike, planets are discussed as a group because of their similarities in terms of density, size, temperature, and chemical make-up. The outer planets are discussed as a group for the same reason. In turn, each planet is discussed individually. You will be able to supplement materials in this section as flyby missions and planetary probes provide more information on their respective NASA websites. More than any other chapter, the Internet resources available to describe the solar system and recent missions are plentiful and should be used.

Suggestions 1. This is an important place to make use of videos such as ―powers of ten‖ showing the vast scale of emptiness that composes the universe.

2. Have the students assist in collecting items that represent the Sun, the Moon, and various planets measured to scale. Use these objects to point out how measurements such as relative size and distance were first performed by the ancients.

3. The biggest danger of studying the solar system is to accidentally ask student to memorize to many facts rather than emphasizing relationships and patterns observed among the planets.

For Class Discussions 1. The first and necessary event in the formation of any planetary system is a. formation of an accretion disk. b. formation of protoplanets. c. initial flare-up of Sun, igniting fusion processes. d. supernovas of massive stars.

2. The motion of a planet as it moves around the Sun is a a. rotation/spin. b. revolution/orbit. c. mass. d. density.

3. Which of the following planets does not belong with the other three? a. Mars b. Venus c. Earth d. Neptune 4. The planet with a very hot surface from a greenhouse effect is a. Mercury b. Venus c. Mars d. Uranus 5. The smallest planet is a. Mercury b. Venus c. Mars

d. Jupiter 6. The largest planet is a. Jupiter b. Saturn c. Neptune d. Uranus 7. Leftovers from the formation of ices from the early solar system might become a. asteroids. b. comets. c. meteors. d. meteorites.

8. The rings of Saturn are made up of a. dust and particles. b. clouds of frozen gases. c. thin layers of rocks. d. sheets of refractive liquids.

9. Craters on the planets and moons of the solar system is the result of meteoroid bombardment that took place a. throughout the history of the solar system. b. about 4 billion years ago. c. 70 million years ago. d. some 6,000 years ago.

Answers: 1d, 2b, 3d, 4b, 5a, 6a, 7b, 8a, 9b.

Answers to End of Chapter Concept Questions 1. The protoplanet nebular model is easiest to describe in stages: Stage A involves the creation of a large, slowly rotating cloud of dust and gases from the supernovas of earlier stars. These supernovas created the material of which the planets are made.

In stage B the cloud begins to undergo gravity-induced collapse. The nebulous cloud begins to rotate faster as it contracts. Most of the mass is pulled into the center, forming the protostar that will become the Sun. The remaining gas and dust forms into an enormous accretion disk.

Stage C begins with the protosun becoming established as a star, perhaps undergoing an initial flare-up that may have blasted away most of the hydrogen and helium surrounding the inner planets. The planets underwent heating sometime early in their formation, allowing the heavier

elements to be pulled to the center. Gases from the interiors of the planets gave them their early atmospheres. Comets were left over in the outer regions of the condensed cloud.

2. The terrestrial planets are mainly rock and iron, while the giant planets are primarily hydrogen and helium with some methane.

3. Mars has inactive volcanic regions, huge systems of canyons, terraced plateaus near the poles, and flat regions pitted with craters. The atmosphere is tenuous and is about 95 percent carbon dioxide. The temperature is cold, about –53 degrees Celsius, and the water present is frozen beneath the surface.

4. The canyons and channels that appear to be riverbeds indicate that liquid water may have existed on Mars at one time. The atmosphere may have been denser, with the abundant carbon dioxide creating a greenhouse effect, causing the temperature to rise to the level where liquid water could exist. As carbonate rocks formed and volcanic activity abated, the planet lost its source of water vapor and carbon dioxide in the atmosphere, so the greenhouse effect declined.

As the planet cooled, the water froze.

5. Jupiter and Saturn are less dense than Earth. Saturn is less dense than water, and if an ocean large enough could be found, the planet could float! These low densities indicate that the planets are made up mainly of light elements, such as hydrogen and helium. In both planets a thick layer of metallic hydrogen surrounds rocky cores. Above this layer is ordinary liquid hydrogen, and above this is the outer atmospheric layer of hydrogen, helium, water ice, ammonia gas, and ammonia clouds. The banded appearance of both planets, more noticeably Jupiter, is from a mixture of sulfur and organic compounds in the uppermost ammonia clouds.

6. Saturn‘s rings are made up of particles of various sizes, ranging from minute dust particles to rocks and ices meters across.

7. Jupiter‘s moon Io has the only volcanic activity known outside Earth and resembles a pizza in certain photographs. Europa is covered with smooth water ice networked with long, straight, dark ridges. Ganymede has the appearance of an active geologic history, and Callisto is the most heavily cratered object in the solar system.

8. The Sun and Jupiter are the two most massive bodies in the solar system, and both have similar chemical compositions. Jupiter, however, does not have the mass necessary to create the conditions required for the fusion reactions occurring in the Sun. 9. One of the theories attempting to explain why the Great Red Spot exists states that the spot is an upwelling of gas deflected from an island or some other surface feature below the atmosphere.

Since both planets are similar in make-up, the same types of storms could arise in both of their atmospheres.

10. Venus and Uranus exhibit spins opposite in sense than the rest of the planets and asteroids.

11. Craters exist on most of the moons in the solar system as well as on the planets Mercury, Earth, and Mars.

12. Mercury is very unlikely to support life. The wide variations of temperature and the lack of an atmosphere make conditions too harsh for life to evolve. Venus, on the other hand, has too much atmosphere. The high pressures and temperatures on the surface, as well as the lack of

water or free oxygen, make life as we know it improbable. Mars may have at one time supported life and is the most viable candidate for extraterrestrial life. This life will probably be microbial survivors from the earlier ages when Mars was warmer and had flowing water on its surface.

13. A shooting star is a meteor burning in Earth‘s atmosphere from atmospheric friction. Most meteors are small particles left by a comet in its orbit. The vast majority of meteors burn away.

14. Asteroids are small rocky or iron bodies thought to be left over from formation of the solar system. The orbits of the asteroids mainly lie in a belt between Mars and Jupiter, leading to speculation that they are the remains of a planet that was somehow broken apart. There is insufficient mass there to suggest it was ever a ―broken‖ planet.

15. Comets are estimated to originate some 30 AU to a light-year or more from the Sun. They are believed to be dirty ice balls left over from the formation of the solar system. For this reason they are studied for information about the early conditions of the solar system.

16. A meteor is an object falling into Earth‘s atmosphere leaving behind a streak of smoke and light. Most meteors are probably rocks and boulders left over from the collision of asteroids, or they are small particles left by a comet in its orbit.

17. Meteorites are meteors that have made it to the surface of Earth. Most meteorites are the remnants of asteroid collisions.

18. A meteorite is defined as an object that has struck the surface of Earth, not the Moon. An object that strikes the Moon or any other planet is probably an asteroid, but more than 30 rocks from Mars and about 30 rocks from the Moon have been found on Earth.

19. The ice and frozen gases that are a part of the comet begin to vaporize as the comet approaches the Sun. These gases carry away small solid particles with them to form the tail of the comet. The dust and solid particles are visible because of reflected light from the Sun. 20. Similarities – both the terrestrial and giant planets are believed to have rocky materials and iron as a core. Differences – the rocky materials of the giant planets are surrounded by tremendous amounts of hydrogen, helium, and methane. Speculations vary, but could include the idea that all planets at one time had hydrogen, helium, and methane atmospheres, but it was blown away from the terrestrial planets with the Sun startup.

21. See sample sketch following:

22. The mass, size, and density of Venus is very similar to Earth. Other than that, Venus is very hot, very high atmospheric pressure, and hostile to life.

23. Answers vary but the probability of life as we know it on each of the other planets is zero.

24. Answers will vary.

25. Comets are believed to be made of the original stuff of which the solar system formed, so studying a comet may provide insights about the formation of the solar system.

End of Chapter Group B Solutions 1. Vsphere=4/3π(d/2)3 and dJupiter= 143,000 km 4 143,000,000 m 3 VJupiter  ( ) ( ) = 1.5 × 1024 m 3 2

2. v  d t



td

v



384,000 km 1,000 km

3. if 25cmscale = 1 × 108 km, then

 384 hours hr

25 cmscale  (108  106 km)  27 cm 8 1  10 km

4. if SpinUranus=17hrs14min, then over the last 24 hours, then Uranus has spun: First, turn 14 min into decimal hours by 14 min 

24 hours 

1 Uranus spin 17.233 hours

1 hr  0.233 hr then 60 min.

 1.4 spins

5. TC = (5/9) (TF – 32) = (5/9) (462F – 32) = 238C, which is a lower number 6. if mgh = 1/2mv2, then v = (2gh)1/2 = (2 × 1.62 m/s2 × 30 m)1/2 = 9.9 m/s

14

Earth in Space

Contents Shape and Size of Earth Motions of Earth Orbit Rotation Precession Place and Time Identifying Place Measuring Time The Earth-Moon System Phases of the Moon Eclipses of the Sun and Moon

Tides

Overview This chapter considers the motions of Earth and Moon as an astronaut returning from some other planet might view them. This approach is intended to impress upon students the observation that Earth is just one of the eight planets of our solar system, which is located in one of countless other planetary systems. As many as a third of the stars in the night sky probably have orbiting planets of their own.

Most students think we know Earth is round based on NASA photographs and are often surprised when we say we’ve known this for thousands of years—the disappearing sailes of a departing ship, the curve of Earth’s shadow on the Moon during an eclipse, the changing of star’s positions as one travels north and south, and the Foucault pendulum. The Foucault pendulum provides evidence of a rotating Earth and you can demonstrate the principle rather easily as a classroom demonstration. Tie a heavy object on the end of a string, and then start the object swinging back and forth in the directions of the students. Now slowly turn the direction you are facing and the students will be able to see that the swing of the pendulum remains in the same plane as the person holding the string moves. If you now swing the pendulum while standing over a spinning globe, students should be able to see that a person on the globe looking up would see what appears to be a pendulum that appears to turn once on its axis during a day.

In the section covering seasons the definition and location of the tropic of Cancer, the tropic of Capricorn, the Arctic Circle, and the Antarctic Circle are discussed. Most students are aware that the Arctic Circle experiences long periods of darkness and long periods of daylight during a year’s time. You can use this knowledge to help explain why the Arctic Circle and the Antarctic Circle are located at certain latitudes.

Few students understand that seasons are caused by Earth’s tilt rather than its changing orbital distance and, likewise, few students understand the phases of the moon, having never systematically observed them. Describing observed patterns is critical to developing students understanding.

Suggestions 1. The principle by which the Foucault pendulum illustrates the rotation of Earth can be illustrated with a yo-yo or with a heavy mass attached to a string. Start the object swinging; then turn on your heels without touching the swinging object. Point out how the direction of the swinging object remains unchanged. A Foucault pendulum for use with a hand rotator is available from many commercial scientific suppliers.

2. A rotating stool and two masses of 2 kg each are ideal to illustrate concentration of mass and its effect on rotation. Ask a student of small stature to sit on the stool with arms extended. Place

a 2-kg mass in each of the student’s hands, and then rotate the stool slowly. While rotating, have the student move the weight toward his or her chest. Observe the change in rate of rotation.

3. Earth photographed from the Moon appears to the eye to be a sphere. Have students make measurements of the polar diameter and the equatorial diameter of Jupiter to illustrate that the spin of a planet produces an oblate spheroid rather than a perfect sphere.

4. To illustrate procession of a rotating object in a gravitational field, use a toy top and spin it at various rates.

5. To illustrate a lunar and a solar eclipse, use two plastic balls of significantly different sizes.

Darken the room and hold the two balls in the light from an overhead projector, slide projector, or filmstrip projector. Move one ball relative to the other to demonstrate both eclipses.

6. The seasons of Earth and the effect of its tilt can be well illustrated in a darkened room with a low-intensity light bulb (25-40 watt incandescent bulb mounted vertically) and a world globe.

Maintain Earth’s 23.5˚ tilted axis away from the perpendicular as you rotate the globe, then move it in a slightly elliptical path about the light bulb. Point out the winter and summer seasons at both the North and South Poles as well as the Northern Hemisphere seasons at Earth’s perihelion and aphelion.

For Class Discussions 1. Earth’s axis of rotation a. is parallel to the ecliptic. b. is perpendicular to the ecliptic. c. is inclined to the ecliptic. d. varies over the course of a year from perpendicular to parallel.

2. Earth’s seasons are a result of a. changes in orbital velocity during a yearly orbit around the Sun. b. variations in the Sun’s output and direction of output. c. the elliptical nature of Earth’s orbit around the Sun. d. the constant orientation of Earth’s axis of rotation.

3. In the Northern Hemisphere the Sun at noon reaches its lowest altitude above the southern horizon at the a. winter solstice. b. summer solstice. c. spring equinox. d. fall equinox.

4. The length of daylight and night are the same everywhere on Earth during a. a solstice. b. New Year day on a leap year. c. an equinox. d. no time since this does not happen.

5. Earth’s axis always has and always will point to the North Star, Polaris. a. Yes. b. No. 6. The most convincing evidence that Earth rotates comes from a. the fact that Earth has seasons. b. the observation that nighttime is always followed by daylight. c. watching a pendulum swing back and forth at different locations. d. measuring sunlight falling into a deep well.

7. You can identify where you are on Earth relative to the equator by using an identifying position based on a. the angle between the North Star and the ecliptic. b. the distance you are from the Greenwich Observatory. c. the altitude of the North Star. d. Earth’s position in its elliptical orbit around the Sun. 8. The time required to observe all phases of the Moon is a. one hour b. one night c. one month d. one year.

9. Leap years are needed to correct the calendar because a. Earth does not complete an exact number of turns during one complete revolution. b. Earth completes a slightly greater number of turns during one complete revolution. c. Earth turns faster around the equator than it does at the poles. d. Earth is slowly spinning down.

10. A solar eclipse can only occur with a a. full moon. b. new moon. c. quarter moon. d. any moon phase.

Answers: 1c, 2d, 3a, 4c, 5b, 6c, 7c, 8c, 9a, 10b.

Answers to End of Chapter Concept Questions 1. (a) The variation in the number of daylight hours is caused by the tilt of Earth‘s axis relative to the plane of the ecliptic. When the North Pole is pointed toward the Sun, the Sun is hitting more of the Northern Hemisphere than the Southern Hemisphere. Conversely when the South Pole is pointed in the direction of the Sun, the Southern Hemisphere receives more sunlight. (b) The variation in the seasons is related to this variation in daylight hours because it is also caused by the axial tilt. When the North Pole is pointed toward the Sun, the Sun strikes the surface of the Northern Hemisphere more directly.

2. On the equator, an almost nonexistent shadow would be observed at noon on the day of the autumnal equinox. (a) In the Northern Hemisphere shadows point northward at noon on the day of the autumnal equinox. (b) A southward-pointing shadow would be seen in the Southern Hemisphere at noon on the day of the autumnal equinox.

3. ―Solstice‖ reflects the words, ―Sun stands still‖ in Latin. The solstices occur when the Sun has is at its most extreme distances from the horizon at noon. This occurs when the axis of Earth is pointing as close to the Sun as possible, or when the Sun is as far north or south as it will travel on the celestial sphere. The solstices occur on about June 22 and December 22.

4. ―Equinox‖ is from the Latin representing ―equal nights.‖ On the equinoxes, both day and night are of the same length. On the equinox, the Sun crosses the celestial equator when viewed on the celestial sphere. The approximate dates for the equinoxes are March 21 and September 23.

5. Earth‘s axis is used to define the north-south position or latitude of a point on the surface.

The North Pole is defined as +90° latitude, while the equator is 0° latitude, and the South Pole is –90°. North south lines run through the poles to identify how far east or west an object is to a reference line. These lines are referred to as meridians of longitude.

6. Answers will vary.

7. The tropic of Cancer and the tropic of Capricorn identify the limits toward the poles where the Sun appears directly overhead during the year. They are located at 23.5° N and 23.5° S latitude respectively. The Arctic and Antarctic circles identify the limits toward the equator where the Sun appears on the horizon all day for at least once during the summer. They are located at 66.5° N and 66.5° S latitude respectively.

8. (a) The movement of the Sun across the celestial meridian is noon. (b) A.M. stands for ante meridiem, or the time before the Sun crosses the celestial meridian. (c) P.M. stands for post meridiem, or the time after the Sun has crossed the celestial meridian.

9. Standard time zones were established to avoid the confusion of having clocks set to local mean solar time. Each time zone is 15° wide in terms of longitude. This was chosen so that there are twenty-four time zones, one for each hour in the day. In this way, the variation in clock time between the time zones is in units of whole hours.

10. Texas is in the Central Time zone. (a) The Eastern Time zone, where Jacksonville, Florida, is located, is one hour later than in the Central Time zone, so 12:00 noon in Texas is 1:00 P.M. in

Jacksonville. (b) Bakersfield, California is located in the Pacific Time zone, where it is two hours earlier than in the Central Time zone. At 12:00 noon in Texas, it is 10:00 A.M. in Bakersfield. (c) At the North Pole, the time is defined to be Greenwich Mean Time, or 7:00 P.M. when it is 12:00 noon in Texas.

11. Since the orbit of the Moon is inclined to Earth‘s orbit, the Moon is usually above or below the shadow of Earth when it passes behind.

12. During a new moon, the Moon is located between Earth and the Sun (but not usually directly between). First quarter is when the Moon has passed new moon and is still on the Sun side of Earth. A half-moon occurs when the Moon has moved beside Earth, while three-quarters is when the Moon begins to move behind Earth. A full moon is when the Moon is farthest from the Sun, and behind Earth. The phases go in reverse order after the full moon to reach another new moon.

13. A ―new earth‖ or an unsunlit disc would be observed from a full moon.

14. During the first 500 million years after the formation of the Sun and planets, there was a period of heavy bombardment by asteroids and meteoroids that covered the Moon with craters.

15. The Moon would be full because if it were in an earlier phase it would rise earlier, while a later phase would rise later. Only when the Moon is on the opposite side of Earth from the Sun will it rise as the Sun sets.

16. The tilt of the orbit of the Moon relative to Earth‘s orbit causes the shadow of the Moon usually to fall above or below.

17. An eclipse of the Sun can only occur during a new moon. During other phases, the Moon is not positioned between Earth and the Sun. 18. (a) Spring tides occur during full and new moons. The alignment of the Sun, Moon, and Earth allows the gravitational effects of the Sun and Moon to combine to make larger tides. (b) Neap tides occur during the half phases when the Sun and Moon are at right angles when measured from Earth.

19. The Moon‘s gravity pulls Earth away from the ocean on the opposite side. This forms a tidal bulge on the outside of Earth‘s path of revolution on the opposite side from the Moon. The bulge on the same side as the Moon is caused by the Moon‘s gravity pulling the water toward the Moon.

20. Similarities – both are the beginnings of seasons recognized from the altitude of the Sun in the sky at noon. Differences – an equinox marks the beginning of summer or winter and occurs when the Sun reaches its highest or lowest altitude in the sky at noon; a solstice marks the beginning of spring or fall and occurs when the sun is situations so daylight and night are of equal length.

21. Earth is closest to the Sun in January. The orientation of Earth‘s axis to incoming sunlight is more important than distance in determining seasons.

22. The plane of the Moon‘s orbit is inclined to Earth‘s orbit about 5° so the shadow from the Moon or the shadow from Earth usually falls above or below the other body, too high or too low to make an eclipse.

23. The difference is a result of the shape of Earth‘s orbit, and the fact that the angles between the plane of the ecliptic and the plane of the equator are different.

24. Answers will vary, but the reason is as follows: The period of twelve hours and twenty-five minutes is half the average time interval required for the Moon the pass directly overhead, and the tidal bulge follows the Moon. The daily rotation of Earth on its axis is 24 hours, which is different from the time required for the Moon to pass directly overhead.

End of Chapter Group B Solutions 1. dEdmonton= 2.384 × 104 km and tsidereal=23hrs56min4sec First, convert 4 seconds into decimal minutes by 4 seconds × 1 min/60 sec = 0.0666 minutes Then convert minutes into decimal hours by (56 min + 0.0666 min) × 1 hr/60 min = 0.934 hours Then, using v=d/t, v = 2.384 × 104 km / 0.934 hrs = 22,300 kph 2. Nassau= 3.632 × 104 km and tsidereal=23hrs56min4sec First, convert 4 seconds into decimal minutes by 4 seconds × 1 min/60 sec = 0.0666 minutes Then determine total minutes as 56 min + 0.666 min = 56.066 minutes

Then, using v=d/t, v = 3.632 × 104 / 56.066 min = 647.8 km/min 3. Because 1 year = 12.381 moon cycles, 33 yrs × (12.381 moons / 1 yr ) = 408 full moons 4. 1 yr = 365.24220 mean solar days and 1 yr = 366.243 sidereal days (a) 75 yrs × 365.24220 mean solar days / 1 yr = 27, 393 mean solar days (b) 75 yrs × 366.243 sidereal days / 1 yr = 27,468 sidereal days 5. If tOctWatch= 11:30am, then figure 14.22 says that mean solar time is off by -15 minutes, so mean solar time should be 11:15am.

6. If the passenger leaves at tSeattle=645 am and then travels for 6.25 hours, then the arrival time in Seattle is 1pm Pacific time. If Maine is 4 hours behind, then landing time in Maine is 5pm Eastern time.

7. If ttotal=2.7 sec, then t1/2=1.35 sec. d = v/t = 3 × 105 km/s ÷ 1.35 sec = 222,000 km

15

Earth

Contents Earth Materials Minerals Rocks The Rock Cycle Earth‘s Interior The Crust The Mantle The Core A More Detailed Structure Plate Tectonics Evidence from Earth‘s Magnetic Field Evidence from the Ocean Lithosphere Plates and Boundaries Present-day Understandings

Overview This chapter is an introduction to the dynamic, ever-changing Earth and how geology seeks to understand the exceedingly slow, natural processes behind these changes. It begins with an account of the materials that make up Earth, including the chemical composition of various Earth materials and the overall structure of Earth.

The solid Earth materials include minerals and rocks. A mineral occurs naturally, it is inorganic in composition, and it has a definite internal structure. The composition of a mineral can vary only between well-defined limits, a feature that accounts for the thousands that geologists have identified. Most minerals are composed of oxygen, silicon, aluminum, and either sodium or potassium. Most of the other elements appear in such small quantities as to be considered impurities. If iron-bearing minerals did not concentrate while in the molten state, iron, along with metals in other ore minerals, could not be mined profitably. Minerals are classified and identified according to various properties, the most useful of which are streak,

hardness, and cleavage. These properties can be determined readily by geologists at a deposition site.

Sedimentary rocks may include organic matter along with naturally occurring minerals.

This category of rock is the product of erosional processes. The study of sedimentary rocks has made scientists aware of changes in living organisms and conditions on Earth when the sediment was laid down. Further correlation of fossil life and layers of sediment, as well as the geologic processes that occur at mid-ocean ridges, have left little doubt that our continents have drifted apart from the gigantic landmass they formed at least twice in the past.

Metamorphic rocks are formed from sedimentary, igneous, or other metamorphic rocks.

Most metamorphic rocks were typically formed as a result of exposure to great pressure and high temperatures. They did not re-melt under these conditions, however. Other metamorphic rocks were formed as hot fluids circulated through them.

The structure of Earth is considered from two viewpoints: (1) considering Earth to have the three main parts of a crust, mantle, and a core, and (2) considering Earth to have a lithosphere (rocky layer), asthenosphere (weak, plastic layer), mantle, outer core, and inner core. Both structural considerations are adequate models, with the second proving more detail that the threepart model.

The concept of plate tectonics is introduced after a discussion of the asthenosphere and sea-floor spreading. As a model, plate tectonics explains volcanic activity, earthquakes, and the diversity of features of relief found on the surface of Earth, as well as on other planets.

Suggestions 1. Specimens can be placed in a display cabinet for students to view. See that each specimen is labeled in terms that the nonscience students can readily grasp.

2. A set of color images can be used to show rock types, formations, and illustrations of the geologic processes that shape the surface of Earth. Choose selections from the many available from supply houses that are most beneficial for the presentation of this and other geologyoriented chapters. Supply houses can also supplement the types of rocks and features that are not present in your location.

3. The petrology collection of rocks and minerals available from supply houses is an excellent way to teach geology concepts for smaller classes. Many specimens from these collections have features that can be distinguished by students in larger classes. Alternatively displaying images from the Internet on a screen for all students to view works well.

4. Cut out the various landmasses from a world map and try to assemble them so the masses fit together as pieces of a jigsaw puzzle. Explain how erosion and other geologic processes might account for areas from which landmasses are missing. Also point out to the students that the best fit between continents is not between shorelines but between continental shelves.

6. If Los Angeles, California, is on a plate moving at a rate of 10 cm per year, calculate how long it would take for Los Angeles to move the distance to where San Francisco, California, is presently located.

For Class Discussions 1. One of these minerals does not belong with the other three.

a. quartz b. gypsum c. mica d. orthoclase 2. One of these rocks does not belong with the other three. a. gypsum b. limestone c. schist d. sandstone 3. One of these rocks does not belong with the other three. a. granite b. marble c. basalt d. rhyolite 4. The rock cycle concept states that all rocks a. are endlessly changing from one type to another. b. will eventually be sedimentary rocks. c. will eventually be metamorphic rocks. d. will eventually be igneous rocks.

5. Volcanoes are least likely to be as frequent on which type of plate convergence? a. ocean-continent b. ocean-ocean c. continent-continent d. all are the same 6. A deep oceanic trench is most likely to be associated with which type of plate boundary? a. divergent b. convergent c. transform d. any of the above

7. Evidence that Earth has a liquid outer core and a solid inner core comes from a. drilling samples. b. volcanoes. c. earthquakes. d. laboratory simulations.

8. About how far would a plate, such as the North American plate, be expected to move in a century? About a. 1 m b. 3 m c. 10 m d. 25 m 9. Convincing evidence for the support of the plate tectonics theory came from studies of a. paleomagnetics. b. meteorites. c. earthquakes. d. shapes of continents.

Answers: 1b, 2c, 3b, 4a, 5c, 6b, 7c, 8b, 9a.

Answers to End of Chapter Concept Questions 1. A rock is an aggregation of one or more minerals and perhaps mineral materials that have been brought together into a cohesive solid.

2. The rock cycle is a concept that an igneous, sedimentary, or metamorphic rock is a temporary stage in the ongoing transformation of rocks to new types.

3. Igneous rocks formed as hot, molten magma cooled and crystallized to firm, hard rocks.

Slowly cooling magma forms coarse-grained intrusive igneous rocks, and quickly cooled magma produces fine-grained extrusive igneous rocks. Sedimentary rocks are formed from sediments.

Conglomerate rocks are made up of large sediments, sandstone contains intermediate-sized sediments, and shale is made up of fine sediments. These rocks are formed through compaction and cementation of the sediments. Metamorphic rocks are previously existing rocks that have been changed by heat, pressure, or hot solution into a different kind of rock without melting.

Sedimentary rock can be changed from shale to slate and then to schist, and finally gneiss. Each stage has a characteristic crystal size and alignment known as foliation.

4. On the surface sedimentary rock would be the most expected, because the forces of erosion are continually working to provide new source material for this type of rock. Deeper into the crust, metamorphic rock would prevail in the higher pressures and temperatures. Even deeper and on the ocean floors, igneous rock would be found in quantity, close to the hot magma from which it forms.

5. Magma is found underground and lava is found on Earth‘s surface. Both are liquid rock.

6. When looking closely at a rock, it is often characterized by the size of the tiny grains that compose it. The larger the crystal grains present, the slower the rock cooled from a magma or lava state.

7. Basalt is dark and fine-grained, whereas granite is light-colored and coarse-grained. Basalt makes up much of the ocean basins. Seafloor spreading allows the hot magma to contact the seawater and cool rapidly to form basalts. Granite is common on the continents because the air is not able to cool magma as quickly.

8. If a rock has basalt‘s chemical composition but it is not fine-grained, it is gabbro and not basalt.

9. As sediments are deposited, the overlying sediments cause an increasing pressure on the sediments below. This process squeezes the grains together, reducing the pore spaces. This compaction of the grains reduces the thickness of the sediment deposit and squeezes out the water. Cementation by chemical deposits between the sediment particles binds the particles together into a rigid, cohesive mass of sedimentary rock.

10. Metamorphic rocks are previously existing rocks that have been changed by heat, pressure, or hot solutions into a distinctly different kind of rock. The temperatures involved must be less than the melting point of the rock, because if the rock melts and re-solidifies, it is an igneous rock and not a metamorphic rock.

11. Information about the core is obtained from seismological data, or earthquake waves that pass through the core; the nature of meteorites, which give information as to the relative abundance of materials in the nebula that condensed to form the planet; and geological data at the surface of the Earth.

12. The asthenosphere is the layer of plastic, mobile, yielding rock located from 130 km to 160 km in depth. The asthenosphere is believed to be one of the important sources of magma that reaches Earth's surface.

13. The magnetic bands are a result of the ―flipping‖ of the magnetic field of Earth several times in the last 150 million years. When the iron minerals in the forming basalt are exposed to this field, they become magnetized and freeze in a record of the field direction as they solidify.

14. The seafloor is new crust that is created in the ridges. Older seafloor is plowed under at the edges of continents in subduction zones to re-melt and possibly migrate back to the spreading ridge. Therefore, all the old rock has already been pushed into a subduction zone in this recycling process.

15. Divergent boundaries occur between two plates moving away from each other. New crust is formed at these boundaries. Convergent boundaries occur between two plates moving toward one another. This is where crust is destroyed to make room for the newly created crust at the divergent boundaries. Transform boundaries occur between plates sliding by each other. Crust is not created or destroyed in these regions; however, many earthquakes are caused by sudden jerks at these boundaries.

16. According to plate tectonics the lithosphere is broken up into a number of fairly rigid plates that move on the asthenosphere. Some plates contain continents and part of an ocean basin and others contain only ocean basins. The motion of the plates and the interaction at the boundaries explain a number of geographic features. Volcanoes are explained by the subduction of one plate below another, mountain ranges are formed by plates colliding or sliding past each other, and new crust is created in suboceanic divergence boundaries.

17. An oceanic trench is a region of great depth that marks a subduction zone of an oceancontinent plate convergence. The trench is formed as the ocean plate is forced beneath the continental plate.

18. The most probable source of earthquakes in southern California is the San Andreas Fault, which is a transform boundary between the Pacific Plate and the North American Plate. If the plates stick together for a time, then violently break apart, an earthquake occurs.

19. This part of the North American Plate is near the plate boundary. This boundary is probably an ocean-continent plate convergence. A deep trench would probably be caused off the coast on the seafloor by the subduction of the oceanic plate.

20. The crust is being created at the mid-oceanic ridges as plates spread apart and new crust forms from the upwelling mantle. This crust replaces that which is forced down into the interior of Earth at subduction zones. The material forced into the subduction zones may cause volcanoes, creating new continental crust, or it may be recycled back to the spreading center to form new crust.

21. Answers will vary, but ice seems to fit the definition of a mineral.

22. Similarities – all rocks are made up of one or more minerals and perhaps other materials.

Differences – igneous rocks formed as a hot, molten mass of rock materials cooled and solidified; sedimentary rocks formed from particles or dissolved materials from previously existing rocks; metamorphic rocks formed from igneous or sedimentary rocks that were deformed or recrystallized by high temperatures and pressures.

23. Volcanoes form where plate boundary convergence is taking place. The eastern United States and Canada are near the center of the North American Place, not a boundary, so you would not expect volcanoes to occur there.

24. Atmospheric gases and vapors, water of the surface, and flowing interior rock materials all cycle. Other planets lack the atmospheric gasses, liquid water, or internal molten rock materials necessary for cycling.

25. Weathering and erosion produce sedimentary rocks, and this is what is occurring on Earth‘s surface.

26. Answers will vary.

27. Answers will vary but should include evidence of an interior with molten or plastic-like materials.

End of Chapter Group B Solutions 1. If v = 3.25 cm/yr and d=5,000 km and v=d/t, then, t=d/v = (5,000 km × 100,000 cm/km) ÷ 3.25 cm/yr = 154 × 106 years 2. If v =20 mm/yr and d = (110 km/longitude ) × 10 longitude = 1,100 km, and v=d/t, then, t=d/v = (1,100 km × 1,000,000 mm/km) ÷ 20 mm/yr = 5.5 x 107 yrs 3. If zwood=9 cm, water=1.00 g/cm3, wood=0.72 g/cm3, and hwood= ? , then h = zwood – zwood(ρwood)/ρwater) h = 9 cm – [ 9 cm × (0.72/1.00) g/cm3]

h = 2.52 cm out of the water 4. water=1.00 g/cm3, contcrust= 2.7 g/cm3, oceancrust= 3.0 g/cm3, mantle= 3.3 g/cm3

 woodcont =  water × ( crust /  mantle ) = 1.0 g/cm3 × 2.7/3.3 = 0.81 g/cm3  woodoceanic =  water × ( crust /  mantle ) = 1.0 g/cm3 × 3.0/3.3 = 0.91 g/cm3

16

Earth’s Surface

Contents Interpreting Earth‘s Surface Processes That Build Up the Surface Stress and Strain Folding Faulting Earthquakes Origin of Mountains Processes that Tear Down the Surface Weathering Erosion

Overview This chapter is about the dynamic, ever-changing Earth and how geology seeks to understand the natural processes behind these changes. First, processes that build up land are considered such as folding, faulting, and other responses to the stresses created by the movement of Earth's plates.

Plate tectonics has changed the accepted way of thinking about the solid, stationary nature of Earth's surface and ideas about the permanence of the surface as well. The surface of Earth is no longer viewed as having a permanent nature, but is understood to be involved in an ongoing cycle of destruction and renewal. Old crust is destroyed as it is plowed back into the mantle through subduction, melts, and becomes mixed with the mantle. New crust is created as molten materials move from the mantle through sea-floor spreading and volcanoes. Over time, much of the crust must cycle into and out of the mantle.

Elevated landscape features are exposed to the elements and undergo weathering and erosion processes that have sculptured them into today's landscapes. The sculpturing, cutting, and transportation actions of running water, wind erosion, and glacial effects are covered after first considering the preparation of the surface through physical and chemical weathering. There are many examples of the results of chemical and mechanical weathering that can be observed by

students during their travels. Many road cuts from the building of highways afford opportunities for students to observe how the relatively smooth faces of these road cuts are slowly disintegrating, with the resulting buildup of talus deposits at the bottom.

Sculpturing of Earth‘s surface takes place so gradually that humans are usually not aware that it is happening. Some events such as a landslide or the movement of a big part of the beach by a storm are noticed. Both the continual, slow downhill drift of all the soil on a slope and the constant shift of grains of sand along a beach are outside the awareness of most people. People do notice the muddy water moving rapidly downstream in the swollen river after a storm. Few, however, are conscious of the slow, steady solution of limestone by acid rain percolating through it. Yet, it is the processes of slow movement, shifting grains and bits of rocks, and slow dissolving that will wear down the mountains, removing all the features of the landscape that you can see. This rate of removal is continual and slow, and would require about 20 million years or so to level the continents to sea level. However, the destructive forces have never won in the past. The constructive forces of diastrophism and vulcanism seem to balance the continual and slow degradation. The look of the landscape has changed and the shapes and sizes of continents have changed. You would expect such changes as the forces of upheaval build up the land and the forces of degradation tear it down.

Suggestions 1. Physiographic relief globes that provide a view of Earth's interior (crust, mantle, and core) and plastic relief globes with a raised relief are available from scientific supply companies as are online 3D visualizations.

2. A set of color images can be used to show rock types, formations, and illustrations of the geologic processes that shape Earth's surface.

3. If a road cut is nearby, ask students to figure out the local Earth history by studying road cuts.

4. Ask the students to list the types of weathering and agents of erosion according to their order of importance in the immediate geographic region. Does the order vary from their home areas?

5. A stream table is extremely useful to illustrate the erosive features produced by running water.

The device uses a mixture of sand of various colors or of sand and several different soils. The stream table should be set in operation and placed on display to permit students to observe changing conditions over time.

6. To illustrate physical weathering, a handful of sharp-edged pieces of limestone can be placed in a jar with a lid and shaken several hundred times. Changes in the sharpness of the rock edges and changes in the composition of the water will show the effects. To illustrate chemical weathering, compare what happens to a sample of limestone in a beaker of water to one in a beaker of water with dilute hydrochloric acid. The chemical action releases bubbles of CO2.

7. Assign students the task of finding and reporting on six different examples of weathering and any examples of erosion they can find on or near the campus.

For Class Discussions 1. The volcanoes along the Washington and Oregon coastline originated from a. ocean-continent convergence. b. ocean-ocean convergence. c. a divergent boundary. d. a transform boundary.

2. The Appalachian Mountains were a result of erosion after an origin of a. folding. b. faulting. c. volcanic.

3. The Sierra Nevadas of California were formed by a. folding. b. faulting. c. volcanic activity.

4. One of the following formed as fault block mountains: a. Black Hills of South Dakota. b. Adirondack Mountains of New York. c. Teton Mountains of Wyoming. d. Mauna Loa in Hawai‘i.

5. One of the following was formed by volcanic activity: a. Black Hills of South Dakota. b. Adirodack Mountains of New York. c. Teton Mountains of Wyoming. d. Mauna Loa in Hawai‘i.

6. Each higher number on the Richter scale means how much more ground movement than the preceding number? a. 2 times more. b. 5 times more. c. 7 times more. d. 10 times more.

7. Which of the following is the most important agent of erosion? a. glaciers b. wind c. ocean waves d. streams 8. Which one of the following does not belong with the other three? a. floodplain b. U-shaped valley c. delta d. meanders 9. Glaciation might leave a deposit called a a. moraine. b. delta. c. dune. d. oxbow.

10. A slowly flowing stream with wide meanders in a wide floodplain is in what stage? a. youth b. maturity c. old age d. rejuvenation 11. Is it possible to have erosion without weathering? a. Yes. b. No. Answers: 1a, 2a, 3b, 4c, 5d, 6d, 7d, 8b, 9a, 10c, 11b

Answers to Concept Questions 1. The principle of uniformity is the frame of reference that the same geologic processes that change rocks seen today are the same processes that changed them in the past. It is based on the assumption that Earth‘s history can be interpreted by tracing it backward from the present to the past. This tracing requires a frame of reference of slow, uniform change.

2. (a) A slow increase of pressure on deeply buried warm layers of rock would create an elastic deformation and then an elastic flow. (b) A slow increase of pressure in cold rock layers would result in a plastic deformation. (c) A quick increase in pressure would result in a break.

3. An anticline is an arch-shaped fold in rock layers, while a syncline is a trough-shaped fold.

4. The presence of folded sedimentary rock indicates that the region has undergone geologic stress in the time since the sedimentary rock was formed.

5. Faulting is generally caused by sudden stress on the cooler, more brittle rock near the surface.

A fault is directly caused by movement between the rocks on either side of a fracture. Folding occurs in deeper rock, which has stress applied more slowly.

6. Normal faulting results from pulling apart stresses such as those associated with diverging plates. Reverse faulting results from compressional stresses that may be from converging plates.

7. The sudden movement of blocks of rock produces vibrations that move out as waves throughout Earth. These vibrations are known as earthquakes. Generally, the motion at plate boundaries creates the stress conditions necessary for the sudden movements of the rock.

8. The theory of plate tectonics would predict that earthquakes would occur at any plate boundary, since stresses on rock always occur in these regions. 9. The time lag between the Swaves and P-waves gives the distance to the earthquake source. The direction to the source is calculated by drawing a circle on a map using the calculated distance as the radius. The point where the circles of three recording stations cross identifies the earthquake source.

10. Quartz sand, clay minerals, metal oxides, and soluble salts are the end products of granite weathering. The clay minerals, and soluble salts are washed away in the weathering process.

The quartz sand and metal oxides are generally removed through erosion.

11. Rainfall carries the products of weathering to a stream through sheet erosion as well as carrying the soluble products of weathering. The small stream moves to larger channels and transports the materials as dissolved rock minerals carried in solutions, as clay minerals and small grains carried in suspension, and as sand and larger rock fragments that are rolled, bounced, and slid along the streambed.

12. A floodplain is the wide, level floor of a valley built by a stream. It gets its name because this is where the stream floods when it spills out of its channel.

13. Youth is characterized by a steep gradient, a V-shaped valley without a floodplain, and the presence of features that interrupt its smooth flow such as boulders in the streambed, rapids, and waterfalls. Erosion eventually brings the onset of the mature stage. The boulders, rapids, and waterfalls are eroded away, the valley smoothed, and the gradient reduced. Meanders begin to form over the wide floodplain, and the higher elevations are now sloping hills rather than steep channel sides. Old age is marked by a very low gradient in extremely broad, gently sloping valleys. The meanders have become broad sweeps across the wide floodplain. The flow is sluggish, and floods are more common.

14. Abrasion from the erosion process of glaciers pulverizes rock into ever-finer fragments, eventually producing a powdery, silt-sized sediment called rock flour.

15. If the stream had an outlet lower than sea level, such as the Dead Sea, the erosion could continue as far down as the stream could flow. Otherwise, at sea level, if the stream lets out into the sea, the flow rate would be very slow and very little erosion would occur.

16. Glacial erosion occurs both by pulling rocks up and along with the glacier as well as by abrasion. There is very little erosion above the glacier, however, causing the valley to be Ushaped. A stream fed by rainfall allows the land above it to be eroded rapidly because it provides an outlet for the rainwater to carry away its sediments. In addition, the stream erosion occurs much faster than that of a glacier, cutting deeply into the land, creating a V-shaped valley.

17. Stream erosion: A stream develops a valley on a widening floodplain. The development of a steam channel into a widening floodplain seems to follow a general, idealized aging pattern.

When the stream is on a recently uplifted land mass, it has a steep gradient, a V-shaped valley without a floodplain, and the presence of features that interrupt its smooth flow such as boulders in the streambed, rapids, and waterfalls. During maturity meanders form over a wide floodplain that now occupies the valley floor. During old age the stream has a very low gradient in extremely broad, gently sloping valleys. The stream now flows slowly in broad meanders over the wide floodplain. Floods are more common in old age since the stream is carrying a full load of sediments and flows sluggishly.

Wind erosion: Two major processes of wind erosion are called abrasion, and deflation. Wind abrasion is a natural sand-blasting process that occurs when the particles carried along by the wind break off small particles and polish what they strike. Deflation, named after the Latin meaning, ―to blow away,‖ is the widespread picking up of loose materials from the surface.

Deflation is naturally most active where winds are un-obstructed and the materials are exposed and not protected by vegetation.

Glacial erosion: Deposits of bulldozed rocks and other materials that remain after the ice melts are called moraines. Plucking occurs as water seeps into cracked rocks and freezes, becoming a part of the solid glacial mass. As the glacier moves on, it pulls the fractured rock apart and plucks away chunks of it. The process is accelerated by the frost wedging action of the freezing water. Plucking at the upper-most level of an alpine glacier, combined with weathering of the surrounding rocks, produces a rounded or bowl-like depression known as a cirque.

18. Stream deposits: When a stream flows into the ocean or a lake it loses all of its sedimentcarrying ability. It drops the sediments, forming a deposit at the mouth called a delta.

Wind deposits: The most common wind-blown deposits are dunes and loess. A dune is a low mound or ridge of sand or other sediments.

Glacier deposits: Glaciers produce a wide variety of materials from rocks, soil, and sediments by the leading edge of an advancing glacier. Deposits of bulldozed rocks and other materials that remain after the ice melts are called moraines. The pulverizing of rock into ever-finer fragments eventually produces powdery, silt-sized sediment called rock flour.

19. Chemical weathering occurs more in a humid climate where sufficient moisture is available.

Not as much chemical weathering occurs in a dry climate because water is necessary.

20. Answers will vary but could include local effects—as the rain forest is cleared away and burned for new fields of tropical agriculture, the thin humus layer is soon exhausted and subjected to leaching without replenishment. The remaining laterite is incapable of sustaining agricultural efforts, sometimes baking into a hard, brick-like layer that is impossible to plow.

Other reasons include the destruction of oxygen-producing vegetation, the worldwide increase in carbon dioxide levels, and the destruction of the plant gene pool.

21. Answers will vary.

22. Answers will vary.

23. Similarities – both elastic and plastic deformation are changes brought about by the application of forces. Differences – elastic deformation is temporary, and the material returns to its original shape; plastic deformation permanently alters the shape of a material.

24. Variables: A ductile condition from confining pressure and deep burial; relatively slow application of compressive stress.

25. More earthquakes occur along a fault plane near the earth‘s surface because rocks near the surface are more brittle than ductile, and relative movement takes place along the fault.

26. Similarities – both are changes in the destruction of solid rock. Differences – weathering is the slow breaking up, crumbling and destruction of solid rock; erosion is the physical removal.

27. Answers will vary.

28. No, sea level is the limit of erosion. Observation of a delta will show that materials are deposited, not eroded at sea level.

Group B Solutions 1.

Richter Magnitude1 = 5.2; Richter Magnitude2 = 9.2;

Energy Difference = ?

Magnitude Difference = Richter Magnitude2 – Richter Magnitude1 = 9.2 – 5.2 = 4 magnitudes Because each magnitude represents 30 times more energy, Energy = 30×30×30×30 = 8.1 × 105 2.

Richter Magnitude1 = 5.2; Richter Magnitude2 = 9.2;

Surface Wave Difference = ?

Magnitude Difference = Richter Magnitude2 – Richter Magnitude1 = 9.2 – 5.2 = 4 magnitudes Because each magnitude represents a surface wave difference of 10 times Energy = 10×10×10×10 = 1 × 104

3. Subtracting the P-wave arrival times from the S-wave arrival times 354 km 540 km 830 km 1150 km 2000 km 12:37:15 12:38:02 12:39:14 12:40:31 12:43:52 12:36:41 12:37:11 12:37:56 12:38:46 12:40:55 34 sec 51 sec 1 min 18 sec 1 min 45 sec 2 min 57 sec 4. If v=725 km/hr, and d=135 km, then what is the travel time? v=d/t  t = d/v = 135 km ÷ 725 km/hr = 0.19 hrs 0.19 hrs × 60 min/hr = 11 min 5. If v=1.45 × 103 km/hr and g = 9.8 m/s2, what is h? v = (2gh)1/2  h = v2/2g = (1.45 × 103 km/hr × 1000 m/km)2 ÷ 2(9.8 m/s2) = 74 km 6. If h = 2.6 × 104 m and g = 9.8 m/s2, what is v0? v = (2gh)1/2 = (2 × 9.8 m/s2 × 2.6 × 104 m)1/2 = 7.1 × 102 m/s 7.1 × 102 m/s × 1 km/1000 m × 60 s/1 min × 60 min/1 hr = 2.6 × 103 km/hr 7. If zcrust = 35 km, mantle=3.3 g/cm3, and crust = 2.7 g/cm3, what is h? h = zcrust - zcrust (crust / mantle)  2.7 g  3   cm h = 35 km - 35 km   6.3 km for the first case  3.3 g 3  cm    2.7 g  3   cm h = 20 km - 20 km   3.6 km for the second case g  3.3  cm3  

Thus the change is 3.6 km – 6.3 km for a total of lowering 2.7 km

8. If x = 326 and y = 39 m – 33 m = 6 m, what is the slope percent?

Slope percent = y/x × 100% = (6 m ÷ 326 m) × 100% = 1.8% 9. Q = vA = 173 m/s × 1.72 × 103 m2 = 2.98 × 105 m3/s 10. If Q = 8.53 × 103 m3/s and A = 5.27 × 103 m2, what is v?

Q=vA  v = Q/A = 8.53 × 103 m3/s ÷ 5.27 × 103 m2 = 2.98 x 103 m/s

17

Earth’s Weather

Contents The Atmosphere Composition of the Atmosphere Atmospheric Pressure Warming the Atmosphere Structure of the Atmosphere The Winds Local Wind Patterns Global Wind Patterns Water and the Atmosphere Evaporation and Condensation Fog and Clouds Precipitation Weather Producers Air Masses Weather Fronts Waves and Cyclones Major Storms Weather Forecasting Climate Major Climate Groups Regional Climatic Influence Climate Change Causes of Climate Change Global Warming

Overview Even if we do not consider the multitude of different chemicals present as the result of pollution, the atmosphere of our planet contains a considerable variety of elements and compounds. The atmosphere is a remarkably pure gaseous solution of nitrogen, oxygen, carbon dioxide, and argon with traces of neon, helium, methane, krypton, hydrogen, xenon, ozone, radon, and so forth.

Only two of these gases (nitrogen and oxygen) make up about 99 percent of the total composition. The composition of gases in the atmosphere is the same percent everywhere around Earth up to an altitude of 25 km (about 15 mi), except for small variations of carbon dioxide.

About half of the radiation from the Sun makes it through the atmosphere. Most of the wavelengths shorter than those of visible light are absorbed by ozone in the upper atmosphere.

About 30 percent of the radiation is reflected back into space. The radiation that reaches the surface is mainly in the form of visible light and longer wavelengths.

The radiation that does reach Earth's surface is absorbed, increasing the temperature of materials on the surface. These materials re-radiate the absorbed energy with longer wavelengths of infrared radiation. The longer wavelengths are absorbed in the atmosphere by molecules of water vapor and carbon dioxide, increasing the temperature. The lower atmosphere is heated from the bottom up and the process is called the greenhouse effect.

If a mass of air is over a particular location for a sufficient amount of time, from several days to a week or so, it begins to acquire nearly homogeneous temperature and moisture conditions from the surface it is over. These horizontally uniform temperature and moisture conditions identify the physical properties of different air masses, which are named from these properties. Thus, tropical air masses are hot, and polar air masses are cold; maritime air masses are moist, and continental air masses are dry. Pressure differences and prevailing wind belts cause massive air masses to break loose from their source regions. This sends a huge mass of polar air southward or a huge mass of tropical air northward. These masses are shifted eastward by the prevailing westerlies. Thus most of the United States can have weather influenced by continental polar air for a few days. Then weather can be influenced by a mass of maritime tropical air, and an occasional weather pattern produced by a mass of maritime polar air. In general, continental polar air drifts farther south in winter and maritime tropical air moves farther north in summer.

Moving air masses bring rapid weather changes along the leading edge of the mass (frontal weather), and slow changes occur after the air mass arrives (air mass weather). Cold air is denser than warm air and wedges under the warm air. A front is usually convex in the direction of movement, acting much as the surface of a huge bubble of air moving across the land. Since warm air is less dense than cold air, a moving warm air mass overrides as it pushes a colder air mass. The overriding air mass produces a series of cloud changes that foretell the coming of a warm air mass. Cirrus clouds and then cirrostratus clouds, which can produce a halo around the Sun or Moon, may appear some 12 hours before a warm front arrives.

Weather forecasting is based on information about air masses, high- and low-pressure systems, and the movement of fronts. Information is gathered from satellite photographs, radar, and other sources of observations and used to construct a weather map, which is analyzed and interpreted for coming changes in different locations.

Climate is the average weather that occurs over a period of years at a given location.

There are a number of different climatic factors that can be used to distinguish one climate from another, but any scheme used is going to be artificial. Boundaries between general climatic patterns are not sharp but are wide zones of transition. Climate regions actually blend into one another gradually.

Suggestions 1. Most students today have highly limited exposure to sky phenomena, and will benefit from providing images. These should include various phenomena of the atmosphere such as why the sky appears blue, northern lights, why sunsets are red, and why airplanes fly in the stratosphere.

2. Demonstrating all of the different data available on weather websites will be useful.

3. On a calm, sunlit day, have students measure air temperatures just above the grass in a field and just above the asphalt or concrete of an adjacent parking lot. Use this information as the basis for a prediction about which way the air is moving near the surface between the grass and parking lot. Use soap bubbles to indicate the direction of air movement and test the prediction.

4. Watch for newspaper reports of Santa Ana and Chinook winds (compressional winds).

Sometimes the results of these warm winds can be very dramatic, melting as much as ten inches of snow or more in a single day.

5. Have students do a literature search to determine how the doldrums, trade winds, and horse latitudes got their names. They could also find how the global wind belts have affected history, for example, what discoveries were a result of the wind belts and how this affected trade.

6. The requirements for the condensation process can be demonstrated with a large, small-mouth jug. Add a small amount of water to the jug and shake it thoroughly to saturate the air. Place your mouth against the clean opening, then blow into the jug to increase the air pressure inside.

Quickly release the pressure, explaining that the expansion will cool the air and result in condensation. Nothing happens when this is done. Now add a smoking match to the jug. When the process is repeated, a fog forms in the jug. Explain the necessary conditions of saturated air, cooling, and the presence of condensation nuclei (provided by the match) in order for condensation to form.

7. Have students record daily temperature, barometric pressure, wind direction, and wind velocity in the morning, at noon, and in the evening. Also have them note cloud cover and amount of precipitation every day. At the end of a week, have a class discussion of correlation between the various factors measured and the type of weather that prevailed during class.

8. Use a series of daily weather maps to identify kinds of air masses and track their movement over time. Look for correlation between the different kinds of air masses and the weather that each brings to your location. Have someone obtain hourly temperature readings for the day before an air mass arrives and for a day after it arrives. Graph the temperature readings and determine when the air mass arrived.

9. Elementary school teachers sometimes claim they can predict a coming storm (low-pressure area) from the noise and activity level of their classes. Some students might be interested in investigating if there is any basis for such claims of changes in the social behavior related to atmospheric pressure changes.

10. The effect of sunlight at different latitudes can be demonstrated with a strip of paper with equally spaced drops of wax from a candle. The paper strip is taped to a globe, running from

pole to pole, with the wax drops on the outside surface. A strong spotlight directed toward the equator will melt the wax drops on the equator first, then poleward.

11. Many new buildings are now constructed with a window overhang or awning so that sunlight shines in a south-facing window in the winter but not during the summer. The size of the overhang or awning can be calculated for your location from a simple three step procedure: (a) determine the time of year that the window should receive full noontime sunlight (e.g., December 21) and the time of year it should receive no noontime sunlight (e.g., March 21); (b) determine the solar altitude at noon for these two dates; and, (c) calculate the overhang or awning length and the height of the overhang or awning above the window. The overhang length is found by dividing the height of the window by the tangent of the solar altitude at noon on the selected summer date, minus the tangent of the solar altitude at noon on the selected winter date. The answer for this part is the length, or how far the overhang or awning should ―stick out‖ from the building. The height of the overhang or awning above the window can be found by multiplying the overhang length by the tangent of the solar altitude at noon on the selected winter date.

12. Some students may be interested in investigating microclimates on your campus. A map of the microclimates can be prepared by investigating plant growth and taking measurements. The influence of a large city on the climate can be investigated by comparing the temperature, precipitation, and humidity of a city with the surrounding countryside.

For Class Discussions 1. An airplane flying at an altitude of 10 km (about 6 mi) is above about how much of the Earth‘s atmosphere? About a. 90% b. 70% c. 50% d. 30% 2. The lower part of Earth‘s atmosphere is mostly heated by a. the Sun b. Earth c. exhaust from combustion engines.

3. Ozone is a. O b. O2 c. O3 4. Without adding or removing any water vapor, a sample of cooling air will have a relative humidity that is a. increasing. b. decreasing. c. the same.

5. The dew point temperature occurs when a. the relative humidity is 100%. b. condensation begins to form. c. the air becomes saturated. d. any of the above.

6. When air that is saturated is cooled, a. some of the water vapor condenses. b. the relative humidity decreases. c. the capacity of air to hold moisture increases. d. the relative humidity increases to greater than 100%.

7. An air from over the Gulf of Mexico makes which type of air mass? a. continental polar b. maritime polar c. continental tropical d. maritime tropical 8. Which one of the following has more associated stormy weather? a. cold front b. occluded front c. warm front d. stationary front 9. A thunderstorm that occurs at 3 AM is more than likely caused by a. a barrier to moving air. b. a cold front. c. convection. d. a warm front.

10. A hurricane is a tropical cyclone with a wind speed of at least a. 75 km/h (46 mi/h) b. 100 km/h (62mi/h) c. 120 km/h (75 mi/h) d. 100 km/h (15 mi/h) 11. The most violent weather disturbance is a a. tornado. b. thunderstorm. c. hurricane. d. cyclone.

12. Clear, fair weather is usually associated with a(n) a. warm front b. cold front c. cyclone d. anticyclone 13. Is it possible for water vapor to condense in clean, cool air? a. Yes. b. No. 14. Which of the following climatic influences would probably make the temperatures of a city more even? a. high altitude b. low altitude c. large body of water nearby d. surrounded by large areas of land Answers: 1b, 2b, 3c, 4a, 5d, 6a, 7d, 8b, 9b, 10c, 11a, 12d, 13b, 14c.

Answers to End of Chapter Concept Questions 1. The greenhouse effect is caused by certain gases in the atmosphere referred to as greenhouse gases. These gases absorb infrared energy emitted by the ground and re-radiate this energy in all directions. Some of this re-emitted energy is again absorbed by the ground, starting the process over, some is absorbed by other molecules in the atmosphere, increasing the temperature, and some is emitted back to outer space. This results in a slowdown of the rate that energy from the Sun escapes into space. Since some of the energy is redirected to the surface, the surface temperature is increased over what it would have been if this effect were not present. The more greenhouse gases, the more the temperature is increased, but adding more glass layers does not increase the temperature in the greenhouse significantly.

2. The ozone shield protects living things on the surface of Earth by absorbing damaging ultraviolet light. Chemical reactions that occur in this layer of the atmosphere require ultraviolet light. Much of the ultraviolet light passing through this layer is absorbed in these chemical reactions. Chemicals used on the surface of Earth have reached this layer of the atmosphere.

They combine with oxygen to form stable compounds; thus, the amount of oxygen available for ozone-forming chemical reactions, which absorb ultraviolet light, is decreasing. The resulting increase in ultraviolet light at Earth‘s surface could have serious health consequences and decrease the output of farms.

3. A horizontal movement of air is called wind. Uneven heating of the atmosphere causes warmer, less dense parts of the atmosphere to be pushed up by cooler, denser parts of the atmosphere. Thus, the Sun provides the energy to drive the wind.

4. In warmer air, the individual molecules have more kinetic energy and are therefore moving faster. These faster-moving molecules collide more violently until their higher speed drives them apart. Since the molecules are farther apart, there are fewer molecules in a unit volume and so the density is less.

5. Heated air is less dense than cooler air. The cooler, denser air pushes the less dense, more buoyant warm air up as the cooler air sinks.

6. High humidity prevents the addition of water vapor from the evaporation of perspiration to the air. Since the evaporation of perspiration carries heat away, when this evaporation does not take place, individuals feel hotter.

7. Clear nights allow a greater loss of infrared radiation by objects than cloudy nights. The air must be cold and calm to allow the water vapor to condense directly onto objects and freeze.

8. A cloud is a collection of water droplets high in the air. A cloud forms when air containing water vapor is cooled and the water vapor condenses onto dust and other small particles in air.

9. Atmospheric stability is a measure of how air moved up in the atmosphere will react. In stable air, any air moved upward will tend to return to its former level. This behavior discourages the formation of clouds, and any clouds that do develop are usually arranged in the horizontal layers of stratus-type clouds. In unstable air, any air moved upward will tend to continue rising. Cumulus clouds usually develop in these types of conditions.

10. Coalescence of cloud droplets involves larger, slower-moving cloud droplets colliding and merging with smaller droplets as they fall. This merging process forms raindrops after many collisions. In the ice crystal process, ice crystals capture water molecules and grow to larger sizes while neighboring water droplets are evaporating. As they grow larger and begin to drift toward the surface, they may coalesce with other ice crystals or water droplets. If they fall during the summer, the warm air below melts the crystals to form raindrops. In winter, it is snow.

11. An air mass is a large, uniform body of air with nearly the same temperature and moisture conditions throughout. Ordinary air does not necessarily have the same temperature and moisture conditions throughout it.

12. (a) The passage of a warm front has clouds forming far in advance of the ground-level base of the front. These high-level clouds are usually followed by thicker and lower stratus clouds as the front advances. A broad band of drizzle, fog, and continuous light rain accompanies clouds. (b) Towering cumulus clouds accompany a cold front, with intense thunderstorms and a rapid temperature drop occurring as the front passes. A rapid shift in wind direction and a rapid increase in the barometric pressure also mark the passage of a cold front.

13. (a) Clouds and cyclonic storms are associated with low-pressure centers. Obviously, low atmospheric pressure is associated with low-pressure centers as well. In the Northern Hemisphere, inward flowing winds wind around counterclockwise to a low-pressure center. (b)

A high-pressure center has outward moving winds that wind around clockwise in the Northern Hemisphere. Higher atmospheric pressures and clear weather are associated.

14. A maritime tropical air mass would probably have afternoon thunderstorms. As the land below the mass warms up during the day, the warmer air near the ground would create thermals in which cumulus clouds could develop from the moist air. These clouds could be the source of the afternoon thundershowers.

15. The first stage begins as convection, mountains, or a dense air mass slightly lifts a mass of warm, moist air in an unstable atmosphere. The lifted air mass expands and cools and cumulus clouds form. An updraft is created as the released latent heat of vaporization warms the air.

Soon the upward moving saturated air reaches the freezing level and ice crystals and snowflakes begin to form. When they become too large to be supported by the updraft, they begin to fall to the surface, melting into raindrops. The mature stage begins when these drops reach the surface.

As the raindrops fall through the air, friction between the falling drops and the cool air produces a downdraft. This mass of air spreads out when it reaches the surface and the leading edge has the appearance of a miniature cold front. This air mass may play a role in creating new cells in front of the thunderstorm. This stage in the life of a thunderstorm has the most intense rainfall, winds, and possibly hail. As the downdraft spreads throughout the cloud, the supply of new moisture is cut off and the thunderstorm enters the final, dissipating stage.

16. A tornado is the smallest, most violent weather disturbance that occurs on Earth. A tornado forms with intense thunderstorms mainly in the spring and early summer afternoons. The states of Texas, Oklahoma, Kansas, and Iowa have the highest incidence of tornadoes.

17. A hurricane is a large, violent circular storm that is born over the warm, tropical ocean near the equator. As a hurricane approaches the air seems unusually calm as a few clouds appear, then thicken as the wind begins to gust. Over the next six hours or so the overall wind speed increases as strong gusts and intense rain showers occur. Thunderstorms, perhaps with tornadoes, and the strongest winds occur just before the winds suddenly die down as the sky clears with the arrival of the eye of the hurricane. It takes the eye about an hour to cross then the thunderstorms and high winds begin again, this time blowing in the opposite direction.

18. Weather is the current condition of the atmosphere. Climate is the larger pattern these weather changes create. ―Climate is what you expect, weather is what you get.‖ 19. Altitude, mountains, large bodies of water, and ocean currents all affect a regional climate.

Average air temperature decreases with altitude. Mountains affect the conditions of passing air masses. Generally the eastern slopes of mountain ranges in the Northern Hemisphere are dryer than the western slopes because water precipitated out of the air as it crossed the mountains.

Large bodies of water tend to moderate the temperature of a region. Ocean currents can influence the temperature of air masses that move from the water to the land, influencing the temperature on the land.

20. As heated air rises, the lower pressure at higher altitudes allows the air to expand. The work required to accomplish this expansion reduces the energy of the molecules of the air, lowering

the air temperature. Since the temperature is now lower than at ground level, snow can exist at higher elevations when it has melted at lower elevations.

21. Fill a long garden hose with water and cap one end. Place the open end in a bucket of water and support the hose vertically. Standard pressure should support (29.92 inches Hg)  13.6 (density of Hg) = 406.912 inches of water. Divide 406.912 inches of water by 12 inches/foot = 33.9 ft of water.

22. Air expands and cools as it rises.

23. Answers will vary.

24. It is convection that moves air, and differential heating is needed for convection.

25. First, find the current condition of temperature and absolute humidity (found from relative humidity at the current temperature). Place pencil point on the temperature and absolute humidity data point. Move pencil to left until it touches saturation line. Follow this point straight down to the x-axis to read the dew point temperature.

26. Dew (or frost) forms directly on objects and the ground. It does not fall, and this is a requirement to be precipitation.

27. Similarities – Both are changes in the weather conditions. Differences – air mass weather conditions undergo slow, gradual changes; frontal weather conditions undergo rapid changes.

28. A tornado is the smallest most violent weather disturbance on earth, but a hurricane covers significantly more area. In addition, hurricanes can sometimes spawn tornadoes in addition to the damage done by sustained hurricane winds.

29. Answers will vary, but could include regional changes caused by altitude, mountains, large bodies of water, or ocean currents.

End of Chapter Group B Solutions 1. If one diameter is 12,742 km = 23.9 cmbasketball, and according to Figure 17.3 we see that 99% of Earth‘s atmospheric mass is within 32 km above the surface, then using a basketball for scale, 32 km 

23.9 cmbasketball  0.06 cm thickness around the basketball 12,742 km Earth

2. If hwrap= 1.27 × 10-3 cm thick, Earth‘sdiameter= 12,742 km, and according to Figure 17.3 we see that 90% of Earth‘s atmosphere is with about 16 km of the surface, then using a ball for scale,

hwrap dball



hatmosphere dEarth

 dball 

hwrap  dEarth hatmosphere



(1.27  10-3 cm) (12,742 km)  1.0 cm ball 16 km

3. Because P1V1 = P2V2, and assuming P1 and V1 occur at sea level, we see V2 

P1V1 (1,013 hPa) (1.50 m3 )   2.71 m3 P2 560 hPa

4. Because P1V1 = P2V2, and assuming P1 and V1 occur at the initial altitude, we see P2 

P1V1 (775 hPa) (1.50 m 3 )   969 hPa V2 1.20 m 3

5. Using Figure 17.15, we see that at 20C, the absolute humidity is 17.5 g/m3. relative humidity 

relative humidity 

18

absolute humidity  100% max absolute humidity at temperature

4g

m3  100%  23% 17.5 g 3 m

Earth's Water

Contents Water on Earth Fresh Water Surface Water Groundwater Fresh Water as a Resource Seawater Oceans and Seas The Nature of Seawater Movement of Seawater The Ocean Floor

Overview Unlike other planets, Earth has so much water covering its surface that it appears blue when viewed from space. Most of this water, however, is undrinkable salty ocean water that covers about 70 percent of the surface. Available water that is not salty, called fresh water, makes up less than 1 percent of all the water on Earth. As humans need fresh water for survival and for industrial purposes, its limited supply causes considerable unrest among nations.

Precipitation is the source of almost all the fresh water found in streams, in lakes, and underground. Each year, about one meter of water falls to the surface when averaged over the whole Earth. About a meter of water is also evaporated into the atmosphere from the surface each year. Fresh water is available because the amounts precipitated and evaporated differ over land and the oceans. The amount evaporated and precipitated varies from location to location, but on the average, more water is precipitated over land than is evaporated from it. This excess of ocean-derived precipitation eventually returns to the ocean to complete the water cycle.

Demand for fresh water is high and can cause shortages in some areas with limited water supplies. The surface and groundwater supplies of fresh water are moving, so they cannot be conserved by nonuse. Supplies of fresh water can be increased by building storage reservoirs, manipulation of the weather, recycling water, and conversion of salt water to fresh water.

Many people point to the ocean, the prevalent environment of Earth's surface, as the answer to water, food, and other needs of our growing population. If the population continues to increase, and if resources of the land continue to become depleted, it seems reasonable to expect that the ocean will be used to provide more and more of humanity's needs. Much remains to be learned about the ocean and the circulation of ocean water, however, and there is concern that the present practice of using the ocean as a convenient place for dumping wastes may cause serious problems on a long-term basis.

Suggestions 1. Demonstrate the distribution of Earth's water by showing a 40-liter aquarium filled with water to represent all the water of Earth. Remove 968 mL to a l liter container to represent all the fresh water on Earth. The water remaining in the aquarium represents all the salt water of the oceans.

To illustrate how the fresh water is distributed, place three 250-mL containers and a medicine dropper in front of the 1-liter container. Pour 760 mL from the ―fresh water‖ container into one of the small containers to represent the amount of fresh water locked up in ice. Pour 200 mL into a second container to represent the amount of fresh water that is underground. Pour the remaining 8 mL into the third container to represent the water in all the rivers, streams, and lakes of the world. A medicine dropper with about three-quarters of a drop from the third container will represent how much water is in the atmosphere at a given time.

2. Use a 250 mL beaker full of marbles to illustrate the concept of porosity. The porosity of the container of marbles is the measured amount of water that you can pour into the beaker divided

by the volume of marbles multiplied by 100. Show the porosity of a brick by measuring the mass of a dry brick, then measuring it again after the brick has soaked in a container of water.

3. In addition to problems of pollution and the cost of cleaning water supplies, the study of fresh water provides many opportunities for discussion of difficult social issues. For example, a new reservoir constructed on a river can provide economic benefits, an increased water supply, new recreational areas, and electric power. On the other hand, construction of the reservoir can displace people and wildlife, destroy areas of scenic beauty by covering them with water, and change the environment. Other social issues concerning water include the question of who should have the right to existing water supplies—farmers, who need water to grow food; industries, which need water for jobs, producing energy and products that people need; or cities, which need water for domestic use by people for cooking, cleaning, and everyday consumption.

4. Using a map showing the major ocean currents, students could predict where a bottle with a message inside might be expected to be found after a week, a month, and a year.

5. Watch for news reports that illustrate how humans are changing the oceans. Examples are ocean waste dumping, oil-well drilling, oil-tanker accidents, city waste disposal, and landfills.

For Class Discussions 1. Generally, most of the freshwater supply is obtained from a. streams or lakes. b. groundwater. c. the ocean.

2. If water is in short supply, who should have first priority for use? a. agriculture b. city domestic use c. industries d. The answer is controversial.

3. How many separate, independent oceans are found on Earth? a. 1 b. 5 c. 7 d. 10 4. What is the origin of all the seawater on Earth? a. Accumulated rainwater over the years. b. It formed soon after the Earth. c. Outer space, by way of comets. d. Volcanoes.

5. How has the composition of seawater changes after millions of years of rainfall? a. Fresh in the beginning, increasing in salinity throughout history. b. It has changed very little. c. The salinity has decreased ever since the last ice age. d. The salinity of seawater varies for ocean to ocean, depending on the location.

6. The flow rate of all of the ocean currents in the world must be equal? a. Yes. b. No. 7. Which one of the following does not belong with the others? a. Gulf Stream. b. California Current. c. Labrador Current.

8. Where does the ocean basin begin? a. At the beach. b. End of continental shelf. c. Beyond continental slope. d. Bottom of submarine canyon.

Answers: 1a, 2d, 3a, 4b, 5b, 6a (sealevel does not change), 7a (warm other cold; also called a stream), 8c.

Answers to End of Chapter Concept Questions 1. Water that falls on land either evaporates, flows downhill to a lower place, or soaks into the ground.

2. The flow of a stream comes from the groundwater that has seeped into the channel.

3. The water table is the boundary between the zone of saturation and the zone above it. A hole that is drilled to the water table is a well. Holes not drilled this far are not wells and do not have groundwater collect in them. Water only accumulates in the portion of the well below the water table.

4. (a) Surface water contains more sediments, bacteria, and possible pollutants than groundwater because it is more active and is directly exposed to the atmosphere. Its higher treatment cost is offset because it is more readily available, but it can be very sensitive to precipitation amounts. (b) Groundwater is naturally filtered as it moves through the pore spaces of an aquifer, so it usually does not need to be filtered. It must be pumped up to the surface, and the energy required for this pumping could be expensive. Dissolved minerals that are usually present in groundwater also may require treatment.

5. Arguments may vary. (a) Agricultural interests claim that they should have priority because they produce the food and fibers that people must have. (b) Industries maintain that they need priority because they create jobs and products that people must have. (c) Cities claim that domestic consumption is most important because people cannot survive without water.

6. Possible ways of extending the freshwater supply include recycling wastewater or desalinating water from the ocean. One of the more radical ideas is to tow icebergs from the polar regions to regions that need water. Conservation is an easily applied method to stretch existing water supplies.

7. Natural processes remove dissolved materials as quickly as the rivers add them. Calcium and silicon are removed by plants and animals to make solid shell, bones, and other hard parts. Other dissolved minerals form solid deposits directly and also make sediments that settle to the ocean floor. These solid deposits and the hard parts of animals and plants are recycled into Earth's interior along with the solid sediments deposited by rivers.

8. Regular groups of low profile, long-wavelength waves are called swell. They form initially in a storm as a chaotic, superimposed mixture of waves. As the waves travel away from the storm area, the longer wavelengths travel faster and last longer than the shorter wavelengths. The longer wavelengths eventually travel alone as a swell.

9. Refraction caused by the shallow water near the shore causes the waves to approach the shore head-on. The part of the wave in the shallower portion refracts because it is traveling slower than the rest of the wave. The circular motion of the water particles reaches the bottom when the depth is about half a wavelength, and friction with the bottom is what slows the shallower end of the wave. This slowdown allows the part of the wave farther from shore to catch up and forces the wave to become parallel to the shore.

10. Wind speed, the length of time the wind blows, and the fetch, or the distance over which the wind blows all affect the formation of waves. Larger waves are produced by strong winds that blow for a long time over a long fetch. In general, longer blowing, stronger winds produce waves with greater wave heights, longer wavelengths, and longer periods, but a given wind produces waves with a wide range of sizes and speeds.

11. As water waves approach the shore, the bottom of the wave begins to reach the bottom.

Friction between the moving particles of water at the bottom of the wave and the bottom result in a slower-moving wave as the wave height increases. The wave front becomes progressively steeper as the bottom part of the wave moves slower than the top. Eventually the top part becomes so steep that it breaks forward and becomes a breaker. The zone where breakers occur is called surf.

12. Water accumulated on shore returns to the ocean by moving beneath the breakers. This weak current might be pushed along the shore by the waves. If the current finds a lower place or channel deeper than the adjacent bottom, a strong stream of water called a rip current bursts out against the waves and returns water through the surf to the sea. A lack of surf, darker-looking waters indicating a deeper channel, and a turbid or muddy streak of water indicate the presence of a rip current.

13. On average, about 98 percent of Earth‘s water exists as liquid, about 2 percent as ice, and a fraction of a percent as water vapor. Over 97 percent of the water is stored in the oceans as salt water, and about two-thirds of the fresh water is locked up in the ice caps of Greenland and the Antarctic and in glaciers. Less than 1 percent of all water on Earth is available as liquid fresh water.

14. An artesian aquifer has groundwater that is under pressure because the groundwater is confined between two impermeable layers and has a recharge area at a higher elevation. The pressure will cause the water to rise in a well drilled into the aquifer, becoming a flowing well if the pressure is high enough.

15. Water particles are moved in a circular motion by a wave passing in the open ocean. On the surface, a water particle traces out a circle with a diameter that is equal to the wave height. The diameters of the circles traced out by water particles decrease with depth to a depth that is equal to one-half the wavelength of the ocean wave. Bottom sediment cannot be moved by waves when the sediment is below the wave base.

16. Answers will vary but could include such ideas as towing glaciers or purifying seawater through the use of solar energy.

17. Answers will vary but could include such ideas as building retention basins where runoff will soak into the ground.

18. Answers will vary, but the two letters should both be convincing.

19. The oceans are well mixed and chemical processes remove dissolved materials.

20. Answers will vary.

21. A river and an ocean current are quite similar in that they both move water and sediment.

However, rivers are entirely gravity driven and flow downhill whereas ocean currents can be driven by wind, salinity differences, temperature differences, and Earth‘s rotation itself.

End of Chapter Group B Solutions 1. Because net water budget = precipitation – potential evapotranspiration, then, net water budget = 980 mm – 635 mm = 345 mm 2. Because net water budget = precipitation – potential evapotranspiration, then, net water budget = 1,778 mm – 1,016 mm = 762 mm 3. Because V=QGA, then V = 305 mm × 9.84 × 102 km2 × (1 m/1000 mm) (1000 m/1 km) (1000 m/1 km) = 3 108 m3 4. Because v = d/t, then v = 3.8 km/28.5 hrs = 0.13 km/h 5. Because v = d/t, then v = 547 m/(365days + 31 days) = 1.38 m/day 6. If volume V=Az and density =m/V, then =m/Az, and we find that, when converted to appropriate units, that mass m=Az mseawater=Az = 1.03 g/cm3 × 4.3 × 105 m2 × 1.7m × (100 cm/1 m) × (100 cm/1 m) × (100 cm/1 m) = 7.53 × 1011 g × 1 kg/1000 g = 7.53 × 108 kg of seawater (with salt) Then, the mass of the salt is the mass of the seawater times the salinity, msalt = mseawater × salinity. msalt = mseawater × salinity msalt = 7.53 × 108 kg × 0.032 = 2.7 × 107 kg of salt 7. If the wave base is ½ of the wavelength, and the slope is y/x, and that critical water depth is 1.33 times the wave height of the breaking waves, then first, Wave base = ½ λ = ½ × 7.0 m = 3.5 m Then, if breaking 31 m offshore and slope is 8.7 cm/m, then the depth of the water is 31 m × 8.7 cm /m or 270 cm. Then, critical water depth is 1.33 times the wave height Water depth = 1.33 × wave height, or wave height = water depth/1.33 Wave height = 270 cm/1.33 = 203 cm 8. Because v = d/t, then t = d/v = 210 m/7.4 m/min = 28 minutes

19

Organic and Biochemistry

Contents Nature of Organic Compounds Hydrocarbons Hydrocarbons with Double or Triple Bonds Hydrocarbons that Form Rings Petroleum Hydrocarbon Derivatives Functional Groups Generate Variety Synthetic Polymers Organisms and their macromolecules Carbohydrates Proteins Nucleic Acids Lipids

Overview The widespread existence of organic compounds should be stressed to students in introducing organic chemistry. It should be pointed out, for example, that the gas, coal, and oil used by our society are all organic compounds. The trees and plants of the forested lands of the earth are also made of organic compounds. Indeed, all animals (including humans) are made up of organic compounds. A very strong case can be made for oil and coal not being used as fuel because they are such marvelous sources of the types of organic compounds needed in our technological society.

Various organic compounds of special interest to students have been included in this chapter. These compounds are used as examples of the classes of hydrocarbon derivatives — alcohols, ethers, aldehydes, ketones, organic acids, and esters. The particular structures are included in the various classes of derivatives to act as attention-getting subjects that will give students greater reason to familiarize themselves with that particular group of organic compounds. For instance, considerable interest can be generated in the classroom by considering the various kinds and types of alcohols and what happens when a bottle of wine ―goes bad.‖ There can be interest in the organic compounds of insect stings and why they hurt. Many are usually interested in the esters responsible for the aroma and flavor of fruit and for the aroma of roses and lilacs. Synthetic polymers, the many types of plastics, and synthetic fibers in use in our

society today are also topics of special interest to students, including the environmental problems created by the plastics.

The importance of bond orientation in chemical compounds can be stressed by pointing out the relatively small difference in the way that the glucose molecules of starch and cellulose are linked. Also to be stressed is the tremendous difference in the chemical and physical properties of starch and cellulose because of the different way in which the glucose units are chemically bound together.

The second part of the chapter contains information that relates to the organic compounds of life, i.e., carbohydrates, lipids, proteins, and the nucleic acids. Be sure to link these with the more traditional discussion of organic molecules used earlier in the chapter.

Suggestions 1. Ask students to list and/or collect various organic compounds available in today's homes.

Remind students that organic compounds are present in many places in the home rather than just in the kitchen.

2. The distinguishing characteristics of organic acids, alcohols, and esters can be contrasted with those of inorganic acids, bases, and salts.

3. The distillates from crude oil and their physical differences make an interesting display for students to observe. You can obtain a sample of crude oil by writing public relations officers of the major oil companies if there is not a local source. The distillates should be sealed in airtight containers to retard evaporation.

4. To illustrate the carbon content in an organic compound, add a sufficient amount of concentrated sulfuric acid to cover the surface of about 100 g of granular sugar that is poured into a beaker. Stir the mixture with a glass rod until a color change appears, then watch the black column of carbon rise above the beaker. Obnoxious odors are produced by this reaction, so use a fume hood, perform the demonstration outside, or display only the result of the reaction to the class.

5. Additional demonstrations: (a) Generate ethylene gas by cautiously boiling 25 mL C2H5OH with 80 mL concentrated H2SO4. Boil the mixture with boiling chips in a Florence flask on a ring stand that is fitted with a thistle tube and gas collection tube in a two-hole stopper. Collect the gas by water displacement, gradually adding all the acid to the thistle tube as you gently boil the mixture. Add an inverted bottle of ethylene to a plastic bag with unripe fruit. (b) Show a few of the esters produced when an alcohol reacts with an acid. (1) In a test, heat 2 mL butyric acid, 2 mL ethyl alcohol, and 1 mL concentrated H2SO4 (dehydrating agent). Ethyl buterate should form, which has the odor of pineapples. (2) To produce amyl acetate, heat 5 mL acetic acid, 3 mL amyl alcohol, and 1 mL concentrated H2SO4. Amyl acetate has the odor of bananas.

For Class Discussions 1. Carbon atoms can form so many different organic compounds because they a. can combine with up to four other carbon atoms as well as other kinds of atoms. b. form covalent bonds by sharing electrons. c. are easily decomposed by heat. d. have a tetrahedral molecular shape.

2. Compounds with the same molecular formulas but different structures are known as a. polymers. b. isotopes. c. isomers. d. polytopes.

3. Which one of the following is a correct name for this hydrocarbon?

a. Methane b. Heptane c. Octane d. Kerosene 4. Of the following, the most stable is a. C2H6 b. C2H4 c. C2H2 d. none of the above 5. Of the following, which is most likely to be found in gasoline? a. CH4 b. C7H16 c. C14H30 d. C16H34 6. Jet fuel, kerosene, coal oil, and lamp oil are names for the same group of hydrocarbons. a. Yes. b. No. 7. All of the different kinds of alcohols

a. have either one, two, or three OH functional groups. b. are safe to drink. c. are denatured. d. have one OH functional group.

8. The building blocks of all proteins are a. monosaccharides. b. esters. c. amino acids. d. triglycerides.

9. Polyunsaturated oils are oils that a. have room for more cholesterol. b. have a higher number of units with double bonds. c. are dry oils, containing no water. d. are used in the manufacture of polymers.

10. Synthetic polymers that are variations of ethylene-derived monomers are manufactured from a. fruit extracts, such as citrus fruit skins. b. fermentation reactions. c. fossil fuels. d. formaldehyde

Answers: 1a, 2c, 3b, 4a (ethane is saturated), 5b, 6a, 7d, 8c, 9b, 10c.

Answers to End of Chapter Concept Questions 1. A compound with carbon as its principal element is defined as an organic compound.

2. Carbon's valence of four allows it to link up with four other carbon atoms, or a wide range of other kinds of atoms, allowing for an almost limitless range of combinations.

3. Ethane has only one structure because it has so few atoms, so it does not have any isomers.

4. Ethylene has a double carbon bond that can be broken to provide sites for single covalent bonds to join the ethylene units. Ethane is an alkane, so it does not have a double carbon bond to break to allow it to form long chains.

5. Each of the four bondable electrons in a carbon atom inhabits an area as far away from the other three as possible. Carbon can share with four other atoms at each of these sites.

6.(a) Natural gas is a mixture of hydrocarbon gases, mostly methane. (b) LPG is liquefied propane or butane. (c) Diesel fuel is a mixture of a group of hydrocarbons that have from fifteen to eighteen carbon atoms per molecule.

7. The octane number scale describes the burning rate of gasoline. The scale is based on pure nheptane, straight-chain molecules that are assigned an octane number of 0, and a multiple branched isomer of octane, 2,2,4-trimethylpentane, which is assigned an octane number of 100.

The ―cracking and reforming‖ process used to increase the octane in unleaded gasoline is more expensive than simply adding a lead compound to the gasoline to increase its octane number.

8. A polymer is a long chain of repeating molecular units. Cellulose is a polymer formed naturally in plants. Polyethylene is a synthetically produced polymer.

9. Carbohydrates – example: table sugar, wood Proteins – example: hair or enzymes Nucleic acids – example: DNA, genetic material in humans Lipids – example: lard, oil For the structural formula of linoleic acid see the text. Linoleic acid is an unsaturated fatty acid because it has double bonds between carbons atoms in the chain.

10. A functional group is the atom or group of atoms in an organic molecule that is the site of a chemical reaction. Functional groups are chemically active because they have multiple bonds that can be broken in order to have chemical reactions, or because they have lone pairs of electrons that can participate in reactions. Examples include: a) ROH alcohol group, 2) ROR' ether group, 3) RCOOH organic acid group, 4) RNH2 Amine group.

11.

The double bonds within the molecule make this an unsaturated fatty acid.

12. The ―sugar‖ referred to in the advertising is sucrose, or table sugar. Dextrose and fructose are classified as simple sugars. Corn syrup is mostly glucose, which is also called dextrose. The advertising is therefore misleading, because the ingredients are sugars even if they are not table sugar.

13. Micromolecules are usually inorganic and smaller than organic molecules which are considered to be macro (large) molecules.

14.

DNA Double stranded

Structure: Bases: ATGC Function: Genetic material

RNA single stranded AUGC assist in protein synthesis

15. The main roles played by protein are  Structural support  Regulation of metabolic activities  Carrier molecules  Catalysts 16. Many people feel that by using a higher octane gasoline in their vehicles that they will get ―better performance.‖ What is the difference between high octane and regular gasoline? The amount of octane will vary depending on the gasoline investigated. Does scientific evidence bear this out? The octane rating of an engine depends on the manufacturer‘s recommendation. In certain situations, the answer is yes. What octane gasoline is recommended for your vehicle?

Answer will vary depending on the engine.

17. There have been some health concerns about the ―additives‖ used in gasoline. What are these additives? Most gasoline contains MMT (methylcyclopentadienyl manganese tricarbonyl). What purpose does It serve? It Is an octane enhancer. What do opponents of using such additives proposed are its negative impact? It is thought that the manganese may be detrimental to health.

18. The so-called ―birth control pill,‖ or ―the pill,‖ has been around since the early 1960s. This medication is composed of a variety of organic molecules. What is the nature of these compounds? The ―pill‖ contains hormones that are members of the lipid group known as steroids. How do they work to control conception since they do not control birth? These hormones at the proper concentration prevent ovulation. What are some of the negative ―side effects‖ and what are some of the related benefits of taking ―the pill?‖ Increased risk of blood clots, stroke and heart attack.

19. Many communities throughout the world are involved in recycling. One of the most important classes of materials recycled is ―plastic.‖ There has been concern that the cost recycling plastics is higher than the cost of making new plastic products.

Go to the Internet and a. Identify the kinds of 'plastics' that are commonly recycled. b. Explain how a plastic such as HDPE is recycled. c. Present an argument for 1. Eliminating the recycling of HDPE 2. Expanding the recycling of HDPE. Answers will vary.

End of Chapter Group B Solutions 1.



V = 20.0 L  = 0.85 g/mL m=?

m  m  V V g     0.85   20, 000mL  mL   g  0.85  20, 000  mL mL =17,000 g =17 kg

2.

C2F4 = 2(12.0) + 4(19.0) = 100

3. Hexane contains the maximum number of hydrogen atoms, so it is saturated.

20

The Nature of Living Things

Contents Part I: The Characteristics of Life What Makes Something Alive?

The Cell Theory Cell Membranes Getting Through Membranes Diffusion Osmosis Controlled Methods of Transporting Molecules Organelles Composed of Membranes Nonmembranous Organelles Nuclear Components Major Cell Types The Prokaryotic Cell Structure

The Eukaryotic Cell Structure Part II: Energy Transformations in Cells Respiration and Photosynthesis The Energy Transfer Molecules of Living Things—ATP Aerobic Cellular Respiration Photosynthesis Part III: Cellular Reproduction The Importance of Cell Division The Cell Cycle The Stages of Mitosis Prophase Metaphase Anaphase Telophase

Overview Most students today have taken courses in biology, but still have highly limited understanding of the interrelationsips between topics. This is a result of too many courses focusing on rote memorization with less emphasis on conceptual understanding. It is a reasonable starting place to assume your students have highly limited understanding of biological topics—including how one describes ―what is alive?‖ We recommend allocating considerable time to defining what it means for something to be alive, with examples and counter examples as important to building a foundation for the rest of the chapter.

The chapter begins by focusing on characteristics typical of living things, and then describes the basics of the cell theory. When presenting mitosis, we include the names of the stages and the events that occur during the stages. The most important material, however, considers the unique result and the significance of this result; the fact that the daughter cells have exact copies of the genetic information of the parent cell preponderates the stages of the process.

For Class Discussions 1. Which is not a characteristic of all life? a. responsiveness b. evolution c. reproduction d. random cell structure 2. All of the chemical reactions within your body are called your a. life b. metabolism c. astrology d. heredity 3. Protoplasm is all the living material a. that makes up a cell. b. inside the cell membrane except the nucleus. c. inside the nucleus. d. inside the cell except the protein material.

4.

Eukaryotic cells are found in A. fungi. b. plants. c. animals. d. All of these answers are true.

5. An outside source of energy (ATP) is required for a. osmosis. b. diffusion. c. active transport. d. None of these answers are true.

6. The most important result of mitosis is the a. production of new varieties of cells to meet changes in the environment. b. exact duplication of the parent cell's genetic information. c. equal division of parent cell's genetic information between the two daughter cells. d. equal distribution of the parent's cytoplasm between the two daughter cells.

7. After cell division, some cells become differentiated. This means that they a. become different shapes. b. become different sizes. c. perform different functions. d. become different in all these ways.

8. The time it takes for cells to divide a. varies, but it takes sophisticated equipment to measure this small difference. b. depends on the health and environment of the cell. c. does not vary at all but is controlled by an internal clock. d. varies widely and unpredictably in cells of the same local area of the same during any specific time period.

9. The order in which the stages of mitosis proceed is a. anaphase, interphase, metaphase, prophase, telophase. b. interphase, anaphase, metaphase, prophase, telophase. c. prophase, metaphase, anaphase, telophase, interphase. d. interphase, telophase, prophase, anaphase, metaphase.

10. The normal purpose of mitosis is a. to make cells smaller b. to produce genetically identical copies of cells c. to make additional DNA d. differentiation

Answers: 1d, 2b, 3a, 4d, 5c, 6b, 7d, 8b, 9c, 10b

Answers to End of Chapter Concept Questions 1.

Structure Chloroplast Endoplasmic reticulum Golgi apparatus Lysosome Mitochondria Nucleus

Function Photosynthesis Transport of materials, sites for protein synthesis Secretion Contains digestive enzymes Site of cell respiration Control center for the cell

2. Diffusion is the movement of molecules as a result of their energy. Osmosis is the diffusion of water through a differentially permeable membrane. Active transport involves energy supplied by the cell to move molecules from an area of low concentration to an area of high concentration.

Facilitated diffusion is movement in the direction from higher to lower concentration but aided by the presence of a carrier molecule.

3.

Cell wall Relatively rigid and thick Composed of many materials but often contains cellulose

Cell membrane Very thin and flexible Composed of lipid and protein

4. Proteins: Nucleus, all membranes, lysosomes, mitochondria, and chloroplasts.

Nucleic acids: Chromatin of nucleus, ribosomes, and nucleolus Carbohydrates: Cytoplasm and cell wall 5. If the eye preparations were not isotonic they either cause the cell of the eye to swell or shrink.

6. Each contains just the right amount of energy to power the job. When the power has been drained, it can be recharged numerous times before it must be recycled.

7. It a series of enzyme-controlled reactions that takes place in the cytoplasm of cells and results in the breakdown of glucose with the release of electrons and the formation of ATP. The electrons are sent to the electron-transport system (ETS) for processing.

8. The electrons are transferred through a series of oxidation- reduction reactions known as the electron transport system involving enzymes until eventually, the electrons are accepted by oxygen atoms to form oxygen ions (O-2)The negatively charged oxygen atoms attract two positively charged hydrogen ions to form water (H 2O).

9.

Glycolysis Krebs ETS

Cytoplasm Mitochondria Mitochondria

10. Light-capturing, Light-dependent reactions. The light-independent reactions will continue as long as the first two reaction sequences have provided enough products.

11. Prophase: The individual chromosomes become visible, duplication of centrioles, spindle begins to form, nuclear membrane disintegrates, and nucleoli disappear.

Metaphase: Chromosomes align at the equatorial plane, no nucleus is present, and spindle formation is completed.

Anaphase: Nuclear membrane still absent, spindle extends from pole to pole, chromosome splits at the centromere, and daughter chromosomes move to separate poles.

Telophase: Daughter nuclei are formed, nucleoli reappear, and cytokinesis occurs.

12. The life of a cell: gap phase one, synthesis, gap phase two, and cell division.

13. DNA replication occurs during interphase.

14. DNA is never visible in the sense that one can directly see it. Even in the electron microscope, one sees only plating or covering of some metal on what was the DNA. Since it is an important part of chromosomes, the question is really asking when are the chromosomes most visible? The answer is metaphase. Chromosomes are most distinct at this stage and most easily counted.

15. The centrioles move away from one another to opposite ends of the cell, forming the cell’s poles and spindle fibers form and grow from one pole to another. As the spindle fibers shorten they cause the chromatids to separate.

16. Some people believe that the common cold can be controlled by using the same antibiotics that are used to control infections such as strep throat. What is the true story? Most medications termed antibiotics have as their target bacteria. Virus are not bacterial and therefore do not respond to such treatment.

17. Local community blood programs are always seeking donors. They want to collect whole blood, red blood cells, and platelets from donors. How do these differ from one another? Whole blood is the fluid tissue that comes directly from the circulatory system. Red blood cells are the non-nucleated cells responsible for the transport of O2. Platelets are specialized fragments of certain blood cells actively involved in the clotting process. What is the value and application for

each in a medical situation? Depending on the amount of blood lost, whole blood may be used as a replacement. Red cells are valuable when there is a need to replenish in cases of hemolytic disease. Platelets can be isolated from donors are supplied to patients who have lost theirs due to certain kinds of cancer and other diseases.

18. The sources of red and white blood cells are undifferentiated cells called stem cells. There is currently a great controversy about the source and use of these cells for research and medical purposes. What is the nature of the controversy? If the stem cells are derived from embryonic tissue, opponents claim that separating them from the embryonic mass is actually the destruction of a human life. What kinds of abnormalities are associated with stem cells? Stem cells have the ability to become any type of specialized cell in the body. There might be used to replenish the bone marrow responsible for the continuous production of white and red blood cells. To what medical purposes might these cells be used? Should stem cell replacement be successful, patients who have lost their various stem cells due to disease may have them replaced by donor stem cells.

19. Cancer occurs when there is a problem with controlling how cells divide and replace themselves. A tumor forms when cells divide in an unregulated manner. As a tumor grows, some of its cells may change and move out of the tumor, enter the circulatory system, and establish new tumors in other places. Scientists are starting to understand how cell growth is regulated.

The picture that is emerging from this research is that many proteins are involved in cell growth regulation. When certain changes occur in the proteins (i.e., histones) that regulate the cell‘s growth, the cell might divide when it should not. Sometimes these mutations are inherited as in cervical cancer. Individuals with these mutations are more likely than others to develop cancer.

Sometimes these mutations occur because of a viral infection such as Human Papilloma Virus, HPV.

End of Chapter Group B Solutions 1. If one atom is about 6.2 × 10–31 m3, then

 1.25 × 10 -13 m 3 plant cell 

1 atom 6.2 × 10 -31 m 3

 2.0  1017 atoms

2. If each carbon atom has a mass of 1.99 × 10–26 kg, then 

48 1 atom  500 kg  100 1.99 × 10- 26 kg

 1.2  10 28 carbon atoms

3. If each cell uses about 2 × 10–17 joules every second, then  1  10 -9 joules 

1 cell 2  10 -17 joules

 5  10 7 cells

4. If thick sheets of paper are 1.0 × 10–4 m thick, then

1 sheet paper 1.0  10 -4 m  5 sheets of paper  5  10 -4 m 

21

The Origin and Evolution of Life

Contents Part I: How Did Life Originate?

Early Attempts to Understand the Origin of Life Current Thinking About the Origin of Life Extraterrestrial Or Earth Origin?

Meeting Metabolic Needs Summary of Ideas about the Origin of Life Major Events in the Early Evolution of Living Things Reproduction and the Origin of Genetic Material The Development of an Oxidizing Atmosphere The Establishment of Three Major Domains of Life The Endosymbiotic Theory and the Origin of Eukaryotic Cells Part II: The Process of Evolution The Development of Evolutionary Thought Evolution and Natural Selection Defining Evolution The Role of the Environment in Evolution Natural Selection Leads to Evolution Genetic Diversity is Important for Natural Selection Genetic Diversity Resulting from Mutation Genetic Diversity Resulting from Sexual Reproduction Processes That Drive Natural Selection Differential Survival Differential Reproductive Rates Differential Mate Selection Acquired Characteristics Do Not Influence Natural Selection The Hardy-Weinberg Concept Accumulating Evidence of Evolution Part III: Speciation

Species: A Working Definition How New Species Originate The Role of Geographic Isolation in Speciation The Role of Natural Selection in Speciation Reproductive Isolation Speciation without Isolation The Tentative Nature of the Evolutionary History of Organisms

Overview This chapter covers a great deal of material about the origin and evolution of living things. It is divided into three parts. Part I presents material about the origin of life. It begins with some historical background to the thinking about the origin of life before discussing current ideas.

There must have been several key steps in the early evolution of life. These include the development of the metabolic processes such as respiration and photosynthesis, the development of genetic material, and the endosymbiotic origin of eukaryotic organisms from prokaryotic organisms. The original Earth probably had an atmosphere that lacked oxygen; therefore, the first organisms would have had to be able to live without oxygen. Oxygen became an important part of the atmosphere after the origin of the process of photosynthesis. A brief discussion of the three domains of life—Bacteria, Archaea, and Eucarya—is presented to help students see how early evolutionary events could have occurred.

Part II deals with the process of evolution. The concept of natural selection is explored in depth. The role of genetic diversity is discussed. The significance of differential survival, differential reproductive rates, and sexual selection are explored in detail. Once students recognize that species are populations of organisms and that the individuals are genetically diverse, it is possible to understand why natural selection takes place and that there can be significant change in a species over time.

Part III focuses on speciation In order for speciation to occur there is a need for an interruption of the gene flow. Geographic barriers are thought to be a common factor leading to speciation and are easily understood. Once the idea of a geographic barrier is presented, students can better understand other methods of isolation. An understanding of speciation leads to thinking about evolutionary change over long time periods that resulted in the kinds of organisms we see on earth today, but that understanding the specific evolutionary path of an organism is tentative and requires reinterpretation as new information becomes available.

For Class Discussions 1. Which of the following is the most likely series of events? a. Earth formed–oxygen in atmosphere–living organisms–ozone

b. ozone–living organisms–plants–organic molecules c. organic molecules–ozone–living organisms–oxygen in atmosphere d. organic molecules–living organisms–oxygen in atmosphere–ozone

2. The first organisms most likely lived in a. the ocean. b. glaciers. c. the atmosphere. d. freshwater streams.

3.

If an organism is able to make organic molecules from inorganic molecules it a. is a heterotroph b. must have been the first organism on Earth c. must use an external source of energy d. cannot break down organic molecules to inorganic molecules.

4.

An oxidizing atmosphere would have a. been present at the origin of the earth. b. developed after eukaryotes were present. c. increased the likelihood of mutation due to ultraviolet radiation. d. been made possible by prokaryotic cells.

5. The endosymbiotic theory is concerned with the development of the cells of a. the Bacteria. b. the Archaea. c. the Eucarya. d. viruses.

6. Which of the following is a likely outcome of the effects of a geographic barrier? a. the same species of birds on island A and island B b. several species of fish in the water between island A and island B c. trees on island A and bushes on island B d. a species of green lizard on island A and a very similar species of brown lizard on island B 7. All of the following would be possible mechanisms of natural selection EXCEPT a. female mice will mate with males that have a particular odor. b. all of the lizards on an island are killed by a hurricane. c. ultraviolet light from the sun kills some members of a species of plant but not others. d. on an island with little food small lizards have more offspring than large lizards.

8. Animal A can breed with animal D and produce a fertile offspring, animal C. If animal A breeds with animal B, they have a sterile offspring, animal E. The animals that belong to the same species are a. A and E. b. A and B. c. A and C. d. B and E. 9. Evolution a. occurs when an individual mutates. b. occurred in the past but is not happening today. c. causes natural selection. d. is demonstrated by changes in the genetic makeup of populations.

10. All of the following discoveries have supported the concept of evolution EXCEPT a. the idea that animals develop skills that their offspring inherit. b. the discovery of fossils of extinct organisms. c. the discovery of the structure and function of DNA. d. the ability to examine and make the structure of the DNA of specific species.

Answers: 1d, 2a, 3c, 4d, 5c, 6d, 7b, 8c, 9d, 10a

Answers to End of Chapter Concept Questions 1. Sequence of events: Reducing atmosphere  first organic molecules  living cell  oxidizing atmosphere  eukaryotes developed 2. Spontaneous generation is the sudden creation of a living thing from nonliving material.

Biogenesis is the theory that all life arises from preexisting life.

3. (a) Ozone is formed from O2 and screens out some ultraviolet radiation. (b) Oxygen was made available for use in the more efficient aerobic respiration process found in almost all living organisms.

4. (a) Mitochondria and chloroplasts have DNA. (b) Mitochondria and chloroplasts reproduce.

5. Redi prepared two sets of jars that were identical in every way except one. One set of jars had a gauze covering. The uncovered set was the control group; the covered set was the experimental group. Any differences seen between the control and the experimental groups were the result of a single variable—being covered by gauze. In this manner, Redi concluded that the presence of maggots in meat was due to flies laying their eggs on the meat and not spontaneous generation.

6. Divide a set of horse hairs into two batches. Place some in distilled water and others in nondistilled water and see in which case worms are observed.

7. Acquired characteristics are those that an individual develops during its life and are not controlled by genes Since these characteristics cannot be transmitted to the next generation through sexual reproduction, they will not influence the gene pool.

8. Natural selection is a process that reduces the frequency of genes for characteristics that are detrimental and increases the frequency of genes that are beneficial within a population of a species. It is accomplished by the death or reduced likelihood of reproduction of those individuals having detrimental genes.

9. Selecting agents include any environmental factor that results in the death or reduced reproduction of individuals within a population. Some examples are: predators that kill certain individuals in a population; low rainfall, which selects those plants and animals that can live with low amounts of water; and low light levels, which selects those individual plants that can live and reproduce in low amounts of light. There are many other examples 10. Lamarck‘s theory that acquired characteristics can be passed through reproduction has been disproved by experiment. It is also inconsistent with our modern understanding of the molecular nature of the gene. Lamarck did not understand the genetic forces that determine phenotype.

11. Wallace traveled extensively and, as a result of his travels, came to the same conclusions about natural selection as did Darwin. He was also influenced by Malthus‘ ideas, as was Darwin. Although today Wallace is often mentioned as an afterthought, it was his essay concerning his ideas about natural selection that prompted Darwin to publish On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life.

12. First of all, evolution only occurs in populations. Populations are groups of organisms of the same species that are able to interbreed and are thus genetically similar. The second point is that genes (specific pieces of DNA) determine the characteristics displayed by organisms. The third point is that the mix of genes (DNA) within populations can change. Thus, evolution involves changes in the genes that are present in a population. By definition, individual organisms are not able to evolve—only populations can.

13. The first involves the phrase ―survival of the fittest.‖ Individual survival is certainly important because those that do not survive will not reproduce. But the more important factor is the number of descendants an organism leaves. An organism that has survived for hundreds of years but has not reproduced has not contributed any of its genes to the next generation and so has been selected against. The key, therefore, is not survival alone but survival and reproduction of the more fit organisms. Second, the phrase ―struggle for life‖ does not necessarily refer to open conflict and fighting. When a resource is in short supply, some individuals survive and reproduce more effectively than others.

14. While sexual reproduction does not generate new genetic information the way mutation does, it generates genetic diversity and allows for the recombination of genes into mixtures that did not occur previously. Each individual entering a population by sexual reproduction carries a

unique combination of genes; half are donated by the mother and half are donated by the father.

During the formation of sex cells, the activities of chromosomes results in new combinations of genes. This means that there are millions of possible combinations of genes in the sex cells of any individual. When fertilization occurs, one of the millions of possible sperm unites with one of the millions of possible eggs, resulting in a genetically unique individual.

15. Because infections evolve, antibiotics do not work for ever, and must be altered.

16. Answer will vary.

17. Answers will vary.

18. Evolution is a fact, because we can observe changes in gene frequency over time and we can detect mutations, which are changes in the genetic material of organisms. However, we cannot, in most cases, state exactly how a specific organisms evolved. We can suggest possible steps in the evolution of organisms but we cannot ever be certain that specific steps were followed.

19. Geographic isolation is necessary for speciation because it prevents interbreeding between two parts of a population. Interbreeding would not permit specific differences to develop.

20. Mules are not capable of breeding and, therefore, do not fit the definition of a species.

21. In order for speciation to occur, the following events are necessary: (a) a geographic barrier dividing a population into two parts, (b) enough time elapses for specific differences to arise by mutation and natural selection, and (c) two distinct populations result.

22. The concept of morphological species is the categorization of living entitites by their appearance, rather than their genetics.

23. Biologists often use specific observable physical, chemical, or behavioral characteristics as guides to distinguishing species. Structural differences are useful but not foolproof ways to distinguish species. However, we must rely on such indirect ways to identify species because we cannot possibly test every individual by breeding it with another to see if they will have fertile offspring. Furthermore, many kinds of organisms reproduce primarily by asexual means.

Because organisms that reproduce exclusively by asexual methods do not exchange genes with any other individuals, they do not fit our biological species definition very well. In addition, the study of fossil species must rely on structural characteristics to make species distinctions since it is impossible to breed extinct organisms.

End of Chapter Group B Solutions 1. number = 2(61-(0.5*61) bacteria number = 2(30.5) bacteria number = 1.5 x 109 bacteria

t = 61.0 min rate = 2t-0.5t

2. If the number of bacteria after 30 minutes is 3(30-7.5) or 322.5 = 5.4 x 1010, then 5.4 x 1010 bacteria x (1.3 x 10-10 m3 / 1 bacteria) = 7.1 m3

3. Growth rate = {(Popnew - Popold) / Popold } x 100/tyears = {(3.76 x 108 – 2.83 x108) / 2.83 x 108} x 100/30 = 1.10%

4. Growth rate = {(Popnew - Popold) / Popold } x 100/tyears = {(1.27 x 108 – 1.03 x108) / 1.03 x 108} x 100/15 = 1.55%

22

History of Life on Earth

Contents The Classification of Organisms The Problem with Common Names Taxonomy Phylogeny A Brief Survey of Biodiversity Domains Bacteria and Archaea Domain Eucarya Acellular Infectious Particles Viruses Viroids: Infectious RNA Prions: Infectious Proteins Geologic Time Early Attempts at Determining Earth‘s Age Modern Techniques for Determining the Age of the Earth Interpreting the Geologic Record Geologic Time and the Fossil Record Early Ideas About Fossils Types of Fossils Using Fossils to Determine the Order of Geologic Events The Geologic Time Scale Paleontology, Archaeology, and Human Evolution Ardipithecus and Other Early Hominins The Genera Australopithecus and Paranthropus The Genus Homo Where Did It All Start?

Overview This chapter looks at the diversity of living things from an evolutionary perspective.

The chapter begins with a discussion of geologic time and the nature of fossils. Fossils provide a window into the life of the past. In addition to providing evidence of previously existing life, fossils can be arranged in a time sequence based on an interpretation of the layers of rocks in which they are found and they can be compared to the layers above and below. It is important to recognize that fossils are not easily formed and that some kinds of organisms, particularly marine organisms with hard parts, are more easily fossilized than terrestrial organisms or those that lack hard parts.

The human fossil record is sparse but it is obvious that there were many kinds of humanlike organisms present in the past and that they have only been present in the last few million years.

The chapter then goes on to discuss the processes used to classify organisms and put them into a meaningful hierarchy. The hierarchical classification system serves several functions. It organizes organisms into groups that make the vast number of organisms easier to comprehend, it seeks to categorize them into natural evolutionary groups, and it seeks to standardize the naming of organisms on a worldwide basis.

Recent studies have clarified the diverse nature of the prokaryotic organisms and they have been reorganized into two major domains; the Bacteria and the Archaea. All of the eukaryotic organisms have been classified into the domain Eucarya. The chapter ends with a discussion of particles that show some of the characteristics of life but have not been clearly established as living things: viruses, viroids, and prions.

For Class Discussions 1. Fungi are in the domain a. Bacteria b. Archaea c. Eucarya d. None of the above is correct.

2. Single-celled organisms without cell walls are found in the Kingdom a. Protista. b. Animalia. c. Plantae. d. Fungi.

3. The genus Homo has been present on Earth for a. over a million years. b. a few thousand years. c. about a billion years. d. a 100 million years.

4. Which one of the following is the correct way to state the scientific name of humans? a. homo sapiens b. Homo sapiens c. Homo Sapiens d. Homo sapiens 5. A cell‘s metabolic pathways can be taken over by the DNA from a a. bacteria. b. fungus. c. virus. d. host.

6. The domain Archaea a. has many species that produce methane b. is older than the domain Bacteria c. consists mostly of organisms that carry on aerobic respirations d. None of the above is correct.

7.

The age of the oldest rocks on Earth is about 3.8 billion years. This has been determined by a. examining the fossils they contain. b. comparing the amount of radioactive materials to the amount of products the radioactive materials convert to. c. carbon 14 dating. d. comparing the rocks to the layers above them.

8. The taxonomic subdivisions from largest to smallest are a. domain, kingdom, phylum, class, order, family, genus, species. b. kingdom, domain, class, phylum, order, genus, family, species. c. domain, kingdom, phylum, order, class, family, genus, species. d. domain, kingdom, order, class, phylum, genus, family, species.

9.

Which one of the following statements about fossils is true? a. The fossil record probably gives evidence of most of the species of organisms that have existed in the past. b. Fossils that are found in the same layer of rock are about the same age. c. Fossils are easily formed. d. Terrestrial organisms are rarely fossilized.

10. Fossils of the early ancestors of modern humans (australopiths) a. are common. b. are all found in Africa. c. clearly show the steps in the evolution of modern humans. d. indicate they were widespread in Africa, Europe, and Asia.

Answers 1c, 2a, 3a, 4b, 5c, 6a, 7b, 8a, 9b, 10b

Answers to End of Chapter Concept Questions 1. Although both Archaea and Bacteria are prokaryotic they differ in their chemical structure and physiology. Bacteria have characteristic molecules in their cell walls that are not present in the cell walls of Archaea. The DNA of Archaea is similar to that of Eucarya. Archaea have a different kind of cell membrane from Bacteria.

2. Taxonomy is valuable in that it helps scientists see the relationships among groups of organisms and seeks to identify organisms in a standard way so that all scientists in the world use the same terminology.

3. Viruses reproduce by entering a cell and taking over the cell‘s structures and using them to make more copies of the virus.

4. Latinized forms of words are used in genus and species names for historical reasons and because scientists want to distinguish scientific names for organisms from common names.

Since only one scientific name is given to each species it makes it easier to know specifically what species is being discussed.

5.

Protista—single celled or colonial; eukaryotic; mostly aquatic Plantae—multicellular; cell wall of cellulose; photosynthesis Fungi—mostly multicellular; cell wall with chitin; heterotrophs Animalia—multicellular; no cell wall; hetertrophs; movement 6. DNA analysis; fossil evidence; life cycle studies; comparative anatomy 7. Answers will vary.

8. Because the early Earth would have been a molten mass, igneous rocks would form as the Earth cooled. Rocks thought to be older than 3.8 billion years have been found but there are still questions about the accuracy of aging. Any rocks that were formed 3.8 billion years ago or earlier would have been subjected to erosion and other geologic processes. Therefore, these rocks are not likely to show fossils of the tiny organisms that could have been present at that time.

However, the nature of the rocks might provide information about the composition of the atmosphere or other conditions that existed at the time the rocks were formed.

9. The Paleozoic and Mesozoic eras both ended with mass extinctions. It has been proposed that bombardment by meteors could have changed the climate enough to cause these extinctions.

Other causes of mass extinctions could have been changes in sea level, volcanic activity, and climate changes.

10. The principle of original horizontality states that any layer of rock that is not horizontal has been subjected to forces that have deformed Earth‘s surface. The principle of superposition states that for undeformed rocks, newer rock is layered on top of older rock. Finally, the principle of faunal succession implies that the same types of fossil organisms lived only briefly and should occur only in rocks that are the same age.

11. Actual preservation of remains, alteration or replacement of remains by mineral material, preservation of the shape of an organism in sediments, and preservation of signs of activity in sediments.

12. Correlation–one of the most important uses of fossils is correlating rocks in one location with those in another.

Paleoenvironments–the kinds of fossils found at a particular locality can help in determining the former environment of a region.

Paleoecology–detailed studies of fossil changes and studies of changes in the type of sediment in which the fossil was found can lead to deductions about how the animal adapted to the environment, its relationship to other organisms, and how ancient communities were structured.

Paleogeography–the geographic distribution of fossils also aids in paleogeography studies. From these studies, it is possible to determine the distribution of land and sea areas, paleolatitudes, ancient shorelines, and land connections.

Paleoclimates–geologists can also determine the paleoclimate or climates for a given region by studying fossil types.

Evidence for evolution–the vertical distribution of fossils provides much support for the idea that living organisms have gradually changed or evolved into their present forms.

Evidence for plate tectonics–the distribution of fossils found on continents that are today separated by an ocean provides evidence that the continents were connected at one time.

13. There were several species of early hominins (australopiths) that had small brains, walked upright, and were herbivores. Fossils of these organisms are only found in Africa. More humanlike species of the genus Homo developed in Africa as well. These organisms had larger brains and were carnivores or omnivores. More recent species have larger brains and show evidence of tool use. Early species are found only in Africa. Fossils of at least three recently evolved species

are also found in Europe and Asia. Homo sapiens is the most recently evolved with a large brain and extensive tool use. H. sapiens may have arisen in Africa or may have arisen simultaneously in Africa, Europe, and Asia from an earlier species of the genus Homo.

14. Answers will vary.

15. Answers will vary.

End of Chapter Group B Solutions 1.

Vap = 800µm3 datom = 0.1 nm = 1 × 10-4 µm ratom = ½ datom = 5 × 10-5 µm Vatom = 4/3πr3atom = 4/3π(5 × 10-5 µm)3atom = 5.2 × 10-13 µm3 Number of atoms =

volume of a.p. volume of an atom

Number of atoms =

800 μm3 5.2 × 10 -13 µm3

Number of atoms  1.5  1015

2. 

volume amoeba volume bacteria



800 m 3 0.1 m 3

 8  103 times larger

3. 

orchidsfungi orchids total

 100%

2  10 4 orchids   100% 2.6567  10 4 orchids  75%

4. unidentified species = total number of species – identified species = 3.0 × 107 species – 9 × 105 species = 2.91 ×107 species 

unidentifi ed species  100% total species

2.91  10 7 species   100% 3.0  10 7 species  97%

23

Ecology and Environment

Contents A Definition of Environment The Organization of Ecological Systems Energy Flow in Ecosystems Community Interactions Types of Terrestrial Communities Temperate Deciduous Forest Temperate Grassland or Prairie Savanna Desert Boreal Coniferous Forest Mediterranean Shrubland (Chaparral) Temperate Rainforest Tundra Tropical Rainforest Tropical Dry Forest Types of Aquatic Communities Marine Communities Freshwater Communities Estuaries Individual Species Requirements: Habitat and Niche Habitat Niche Kinds of Organism Interactions Predation Parasitism Commensalism Mutualism Competition

Competition and Natural Selection The Cycling of Materials in Ecosystems The Carbon Cycle The Nitrogen Cycle The Phosphorus Cycle Nutrient Cycles and Geologic Time Bioaccumulation and Biomagnification Population Characteristics Genetic Differences Age Structure Sex Ratio Population Density The Population Growth Curve Population-Size Limitation Limiting Factors to Human Population Growth Human Population Growth and the Global Ecosystem

Overview This chapter is designed to present the fundamentals of ecology and emphasize the human being as an animal in a complex ecosystem, the biosphere. Today‘s world forces students to make decisions that influence their environment. This means they should be provided with a basis for making wise decisions. The first portion of the chapter provides some basic definitions needed to understand the material that follows.

The flow of energy necessary to support life begins with the role of the green plants—the producers—and proceeds through the trophic levels occupied by the various types of consumers.

This discussion is followed by a section that describes how organisms interact with one another in food chains. The complexity of a food web and the flow of energy through these food webs serve as an introduction for the explanation of communities and their respective roles in an ecosystem. Included is a discussion of the major types of terrestrial biomes and major types of aquatic ecosystems.

The next major section of the text deals with individual organisms interact with their surroundings and including other organisms. It introduces the concepts of habitat, niche predation, parasitism, commensalism, mutualism, and competition.

The next major section deals with how materials are cycled through ecosystems and includes detailed descriptions of the carbon, nitrogen, and phosphorus cycles.

The chapter ends with a discussion of population biology. It describes how different populations of the same organism can differ in genetic diversity, age structure, sex ratio, and population density. The classic population growth curve is discussed along with the concept of carrying

capacity. It introduces the various factors that can act as control mechanisms for growth. These mechanisms include both the external factors of food, energy, predators, and disease, and internal factors such as social behavior and freedom of choice.

The ends with a discussion of the implications of population biology to humans and how a growing population affects the world ecosystems.

For Class Discussions 1. Which of the following is an example of a biome? a. tundra in Alaska b. the lawn at your college c. sugar cane fields d. Australia 2. The greatest diversity of animals is found in the a. tropical rainforest. b. boreal forest. c. tundra. d. temperate forest.

3. The difference between an ecosystem and a community is that the ecosystem has something a community does not have; the ecosystem has a. producers. b. consumers. c. nonliving parts. d. interacting species.

4. If it were part of a food web a fish could be eaten by a. humans. b. birds. c. cats and dogs. d. All of these answers are true.

5. An example of community is a. this class. b. various kinds of organisms living in the soil. c. bees in a hive. d. goldfish in a jar.

6. Which is a food chain? a. grass-grasshopper-horse b. fish-grasshopper-snake c. light-grass-human d. grass-cow-human

7. Which of the following is not a community? a. a group of different species living in a pond b. a forest c. a population of rabbits d. a pine tree and the organisms that live on it 8. If a habitat is where an organism lives, a niche is a. how the organism functions. b. what happens to the organism. c. what the organism does. d. All of these answers are true.

9. Which one of the following would result in an increase in the rate at which a population grows? a. reduction in the birthrate b. reduction in the number of females c. reduction in the death rate d. reduction in the number of males 10. As the size of a population approaches the carrying capacity a. the number of births and deaths are about equal. b. the population is in the lag phase. c. the population decreases d. the biomass decreases.

Answers: 1a, 2a, 3c, 4d, 5b, 6d, 7c, 8d, 9c, 10a

Answers to End of Chapter Concept Questions 1. In most ecosystems photosynthetic producers trap energy and make it available to other organisms. The energy travels from one organism to another, as one organism eats another, with a loss of energy each time it enters another organism. The various organisms represent trophic levels or stages of energy flow.

2. Sunlight is the source of energy. Plants serve to convert light energy into food energy. Second law of thermodynamics—as energy is converted from one form to another useful form, energy is lost. In ecosystems, about 90% of the energy is lost as it flows from one trophic level to the next.  Consumers are organisms that obtain energy by eating other organisms.



Decomposers obtain energy by breaking down complex organic molecules of dead organisms and organic mater into simple inorganic molecules.  Herbivores are animals that eat plants.  Carnivores are animals that eat animals.  Omnivores are animals that eat both plants and animals.

3. In the flow of energy from the herbivore to the carnivore, there is a loss of usable energy. This loss of energy means that less life can be maintained at the higher trophic level.

4. Predominant abiotic factors are the following: a. Temperate deciduous forest 1.seasonal climate with winter, spring, summer, fall 2.enough rainfall to support trees b. Boreal coniferous forest 1.long, cold winters 2.high altitude or latitude c. Desert 1.low amount of rainfall throughout the year 2.not necessarily hot d. Tundra 1.long, cold winter 2.permafrost e. Tropical rainforest 1.lack of frost 2.high rainfall f. Savanna 1.seasonal rainfall—wet and dry seasons 2.frequent fires 5. No. As energy moves through the ecosystem, some of it is lost in the form of heat. Material can be recycled, but energy cannot be recycled.

6. The students, in describing their niches, might describe the living conditions, job status, type of food, kind of clothes, dependents, health condition, and so on.

7. Parasitism, commensalism, and mutualism all involve a close relationship that is beneficial to one of the members of the association. The difference is that the other member of the association is affected differently in each case. In parasitism, the host is harmed; in commensalism, the host neither benefits nor is harmed; in mutualism, each member benefits.

8. The atom of carbon may be fixed into a carbohydrate by photosynthesis in the plant. If a herbivore eats the plant, the atom of carbon may be changed through digestion and tissuebuilding processes into a part of the herbivore. This may in turn be taken up by a parasite feeding on the herbivore, and eventually this carbon will be returned as carbon dioxide to the atmosphere by a decomposer breaking down the dead parasite. All organisms (including plants) carry on respiration and release carbon dioxide

9. Bacteria fill the following roles in the nitrogen cycle:  Decomposer bacteria break down protein and release ammonia  Symbiotic nitrogen-fixing bacteria convert atmospheric nitrogen to ammonia  Free-living nitrogen-fixing bacteria convert atmospheric nitrogen to ammonia  Nitrite bacteria convert ammonia to nitrite.  Nitrate bacteria convert nitrite to nitrate.  Denitrifying bacteria convert nitrite to atmospheric nitrogen.

10. Organism that live a long time; have relatively few young; and provide care for their young.

11. Under conditions of intense competition two species of organisms can continue to exist if one of the species migrates to a new location or the organisms evolve to fill slightly different niches.

12. The human population growth curve is currently growing rapidly. It also displays a long lag phase. There is currently no indication that a stationary growth phase is imminent, but it must come eventually.

13. Possible answers: (a) More shade under the bridge; (b) cooler temperatures under the bridge; (c) increased humidity under the bridge.

14. It is possible that their variety will also decrease due to a dramatic change in food types available to other kinds of herbivores.

15. Answer will vary. Students should consider trophic levels when describing their web.

16. Reduce the number of females by trapping or killing them. Or, sterilize all the females.

17. Plants must take up sulfur from the soil and incorporate it into their proteins. Animals eat plants and other animals and obtain sulfur from the proteins they consume. Decomposers will break down protein and release sulfur to the soil and atmosphere.

18. The following questions are relevant:  How much energy does it take to raise the crops?  How much land would it take to raise the crops to produce the biofuels?  What is the cost of producing these fuels compared to producing, finding, and developing fossil fuel sources?

19.Answers will vary. Several might include:  Controlling reproduction of endangered species by confinement and controlled breeding.  Limit hunting or harvesting to allow more young to survive to adulthood.  Establish reserves where organisms can better survive.

20. mutualism: families, any example of teamwork, the buddy system when swimming, etc.  parasitism: people who copy your homework, panhandlers, people who constantly borrow from you, etc.  commensalism: a person who eats your leftover food, imitating the successful behavior of a colleague, etc.  competition: sport teams, economic competition, etc.

End of Chapter Group B Solutions 1. If fruits and vegitables equal the Bear‘s weight times 33%, then =200 lbs × 0.33 = 66 lbs

2. If percentage of energy lost is the ratio of energy lost to energy available, then 

energy lost  100% energy available



150 calories - 30 calories  100% 150 calories

 80%

3. If available calories is the total calories time percent available, then = total calories × percent calories available = 1000 calories × (100% - 40% - 40%) = 1000 calories × 20% = 1000 calories × 0.20 = 200 calories available

4. Nitrogen produced by hogs is the rate of N production times the total manure 

14 lbs N  20,000 lbs manure 2,000 lbs manure

 140 lbs N

Nitrogen produced by sheep is the rate of N production times the total manure 

23 lbs N  20,000 lbs manure 2,000 lbs manure

 230 lbs N

Then, 230 lbs N – 140 lbs N = 90 lbs N Sheep produce 90 lbs more N in a year, when compared to hogs.

24

Human Biology: Materials Exchange and Control

Contents Homeostasis Exchanging Materials: Basic Principles Transporting Materials: The Circulatory System The Nature of Blood The Heart Arteries, Veins, and Capillaries Skin: The Body‘s Container Primary Functions of the Skin The Structure of the Skin Other Features of the Skin Exchanging Gases: The Respiratory System Structure and Function of Lungs The Mechanism of Breathing

Homeostasis and Breathing Obtaining Nutrients: The Digestive System Processing Food Nutrient Uptake Nutrition Kinds of Nutrients Waste Disposal: The Excretory System Control Mechanisms The Structure of the Nervous System The Nature of the Nerve Impulse Activities at the Synapse Endocrine System Function Sensory Input Chemical Detection Light Detection Sound Detection Touch Output Mechanisms Muscles Glands Growth Responses

Overview This chapter begins with a survey of four systems of the body—the circulatory, respiratory, digestive, and excretory systems. These four systems are involved in the exchange of materials across membranes. This exchange is limited by the amount of surface area present. All of these systems have special mechanisms to provide large surface areas that allow for necessary exchanges.

The circulatory system consists of a pump, the heart, and blood vessels that distribute the blood to all parts of the body. The blood is a carrier fluid that transports molecules and heat. The exchange of materials between the blood and body cells takes place through the walls of the capillaries. The contraction of arterioles can regulate the flow of blood, so blood can be sent to different parts of the body at different times. Hemoglobin in red blood cells is very important in the transport of oxygen.

The respiratory system consists of the lungs and associated tubes that allow air to enter and leave the lungs. The diaphragm and muscles of the chest wall are important in facilitating breathing. In the lungs tiny sacs called alveoli provide a large surface area in association with capillaries, which allows for rapid exchange of oxygen and carbon dioxide.

The digestive system is involved in disassembling food molecules. This involves several processes: grinding by the teeth and stomach, emulsification of fats by bile from the liver,

addition of water to dissolve molecules, and the action of enzymes that break complex molecules into simpler molecules for absorption. The intestine provides a large surface area for the absorption of nutrients because it is long and contains many tiny projections of the wall that increase surface area. Once absorbed, the materials travel to the liver, which modifies molecules.

The excretory system is a filtering system of the body. The kidneys consist of nephrons into which the circulatory system filters fluid. Most of this fluid is useful and is reclaimed by the cells that make up the walls of these tubules. Materials that are present in excess and those that are harmful escape. Some molecules may be secreted into the tubule, as well, before being eliminated from the body.

The final section compares the control functions of the nervous and endocrine systems, the kinds of effects they have, and their characteristics. The nerve impulse is the result of sodium ions entering the cell as a result of a change in the permeability of the cell membrane. Thus, a wave of depolarization passes down the length of a neuron to the synapse. The axon of a neuron secretes a neurotransmitter, such as acetylcholine, into the synapse, where these molecules bind to the dendrite of the next cell in the chain, resulting in an impulse in it as well. Cholinesterase present in the synapse destroys acetylcholine so that it does not repeatedly stimulate the dendrite.

Several different kinds of sensory input are possible. Many kinds of chemicals can bind to cell surfaces and be recognized. This is probably how the sense of taste and smell function, although the details of how molecules are recognized are not fully understood. Light energy can be detected because light causes certain molecules in the retina of the eye to decompose and stimulate neurons. Sound can be detected because fluid in the cochlea of the ear is made to vibrate and special cells detect this movement and stimulate neurons. The sense of touch consists of a variety of different receptors that respond to pressure, cell damage, and temperature.

The nervous and endocrine systems cause changes in the activities of muscles and glands.

Skeletal muscle responds to nervous stimulation, resulting in movements of the skeleton.

Smooth muscle and cardiac muscle have internally generated contractions that may be modified by nervous stimulation or hormones.

Glands are present as two types, exocrine glands that secrete through ducts into the cavity of an organ or the surface of the skin, and endocrine glands that release their secretions into the circulatory system. Digestive glands and sweat glands are examples of exocrine glands.

Endocrine glands such as the ovaries, testes, and pituitary gland change the activities of cells and are often responsible for responses that require growth over a period of time. It is becoming clear that the endocrine system and the nervous system are interrelated. Actions of the endocrine system can change how the nervous system functions, and the reverse is also true. Much of this interaction takes place in the brain-pituitary gland association.

For Class Discussions 1. All of the following occur at the synapse between nerve cells except

a. neurotransmitters are released. b. neurotransmitters are destroyed. c. enzymes are active. d. neurotransmitters flow both ways across the synapse.

2. The normal flow of blood through the heart would be a. right atriumright ventriclelungsleft atriumleft ventricle. b. right atriumleft atriumleft ventricleaorta. c. lungsright atriumright ventricleaorta. d. right atriumright ventricleaortaleft atriumleft ventriclelungs.

3. The normal flow of blood would be a. heartcapillaries arteriesveinsheart. b. heartarteriescapillariesveinsheart. c. heartveinscapillariesarteriesheart. d. heartveinsarteriescapillariesheart.

4. Sense organs send their information to a. endocrine glands and the central nervous system. b. the central nervous system. c. skeletal muscle. d. skeletal, cardiac, and smooth muscle.

5. Chewing is important because it a. alters the food chemically. b. adds enzymes that cause starch, proteins, and fats to break down. c. increases the surface area exposed to the action of enzymes. d. is required by your mother.

6. Gastric juice a. is very acidic. b. digests fats. c. assists the function of saliva. d. is produced by the pancreas.

7.

Hormones are a. able to regulate growth. b. produced by exocrine glands. c. transported along the length of nerve cells. d. not controlled by the nervous system.

8.

The breathing rate is controlled by a. the amount of oxygen in the blood. b. the pH of the blood. c. how fast the heart is beating. d. the number of capillaries present in the lungs.

9. In which of the following ways are the nervous and endocrine systems similar? a. Both contain cells that carry impulses. b. Both secrete molecules that attach to other cells. c. Both typically are fast acting. d. Both typically use the circulatory system to transport molecules.

10. Which of the following is true for the brain? a. All parts of the brain are the same in terms of the kinds of neurotransmitters. b. Several kinds of neurotransmitters are used to store information. c. Different parts of the brain are sensitive to different neurotransmitters. d. Neurotransmitters are distributed to various parts of the brain.

Answers: 1d, 2a, 3b, 4b, 5c, 6a, 7a, 8b, 9b, 10c

Answers to End of Chapter Concept Questions 1. The primary functions of the heart and blood vessels are as follows. The heart is a pump that causes the blood to move. Arteries carry blood from the heart to the body. Veins carry blood from the body to the heart. Arterioles regulate how much blood flows to a part of the body.

Capillaries are the site of exchange of molecules between the blood and cells of the body. The blood is the fluid that transports molecules from place to place.

2. The digestive system increases its ability to absorb nutrients by reducing the size of the molecules so that they can pass through the wall of the intestine easier, by having a large surface area across which the molecules can move, and by having large numbers of capillaries in the walls of the small intestine.

3. Breathing involves the cyclic contractions of the diaphragm and muscles of the chest wall.

Their contraction increases the volume of the chest cavity, which causes a decrease in pressure and thus air flows into the lungs. The relaxation of these muscles causes the pressure inside the chest wall to increase and air is forced out of the lungs.

4. A chemical pump constantly transports sodium ions from the interior of the cell to the exterior. Therefore there are more sodium ions outside than inside and the cell and the cell membrane is polarized (there is a voltage difference between the inside and the outside of the cell). When a nerve cell is stimulated the permeability of the cell membrane is changed and sodium ions diffuse into the cell and that portion of the cell membrane is depolarized. When one portion of the cell membrane is depolarized it causes an adjacent section of the membrane to change its permeability and the impulse moves down the nerve cell.

5. Acetylcholine is a neurotransmitter. It is released at the end of the axon of one nerve cell and diffuses across the synapse where it attaches to receptor sites on the dendrites of the other nerve cell causing it to carry an impulse.

6. The nasal epithelium detects molecules. The taste buds detect molecules. The cochlea of the ear detects sound vibrations. The retina of the eye detects light.

7. The central nervous system consists of the brain and spinal cord and is resposible for integrating input from sense organs and generating messages that cause glands and muscles to act. The peripheral nervous system consists of nerve fibers that connect sense organs, muscles, and glands to the central nervous system. It is divided into two functional systems, the motor system that carries information from the central nervous system to muscles and glands and the sensory system that carries information from sense organs to the central nerous system.

8. When a nerve cell is stimulated, a small portion of the cell membrane depolarizes as Na+ flows into the cell through the membrane. This encourages the depolarization of an adjacent

portion of the membrane, and it depolarizes a short time later. In this way a wave of depolarization passes down the length of the nerve cell. Shortly after a portion of the membrane is depolarized, the ionic balance is reestablished. It is repolarized and ready to be stimulated again.

9. Large, multicellular organisms need a circulatory system because organisms and their cells must exchange materials through their surfaces and most cells in large organisms are buried within the organism. The circulatory system serves to carry molecules to and from cells that are deep within the organism.

10. The villi and the long length of the small intestine increase the surface area, which increases the ability of the intestine to absorb nutrients.

11. Answers will vary. One possible answer: when you run up a hill, your leg and arm muscles move in a coordinated way to provide power. They burn fuel (glucose) for energy and produce carbon dioxide and lactic acid as waste products, which tend to lower the ph of the blood. Your heart beats faster to provide oxygen and nutrients to the muscles, you breathe faster to supply the muscles with oxygen and get rid of carbon dioxide, and the blood vessels in the muscles dilate to allow more blood to flow to them. As you run, you generate excess heat. As a result, more blood flows to the skin to get rid of the heat and sweat glands begin to secrete, thus cooling the skin.

13. Plasma, cellular material, and platelets.

14. The larger, more powerful left side of your heart receives oxygenated blood from your lungs, delivers it through your aorta to all parts of your body, and returns it to your right atrium by way of large veins known as the superior vena cava and inferior vena cava.

15. The primary technical problems would be the difficulty of making extremely thin-walled tubes that were permeable to some materials but not others.

16. The larger the surface area exposed the greater the amount of heat transfer possible.

17. The major nutrients missing from the diet would be calcium and since vitamin D is typically added to milk it may be in short supply as well.

18. Similarities - Both are communication systems. Both use the transfer of molecules to accomplish their function. Both involve actions that take place at the cellular level. Differences Nervous responses are generally rapid, endocrine slow. Endocrine responses often involve growth, nervous does not. Nervous involves direct transfer of information from one cell to an adjacent cell. The endocrine system does not.

19. The lungs consist of many tiny sacs called alveoli. The small intestine is long and has many finger-like villi. The kidney contains millions of tubular nephrons.

End of Chapter Group B Solutions 1.

Heart Rate = 80 beats/minute time = 24 hours = 1,440 minutes

Heart beats = heart rate × time = 80 beats/minute × 1,440 minutes = 115, 200 heart beats

2.

weightRBC

= weightman × % weightblood × % weightRBC = 196 lbs × 9% × 43% = 196 lbs × 0.09 × 0.43 = 6.4 lbs

3. 

calories FAT  100% calories T OT AL 9 calories FAT 1 g fat  100% 220 calories T OT AL

12 g fat  



108 calories FAT  100% 220 calories T OT AL

 49%

4. CO2 produced

= percent of CO2 produced × amount of air exhaled = (4% - 0.04%) × 500cm3 = 3.96% × 500cm3 = 0.0396 × 500cm3 = 19.8 cm3

25

Human Biology: Reproduction

Contents Sexual Reproduction The Mechanics of Meiosis Human Sexuality from Different Points of View Chromosomal Determination of Sex and Early Development Chromosomal Abnormalities and Sexual Development Fetal Sexual Development Sexual Maturation of Young Adults The Maturation of Females The Maturation of Males Spermatogenesis Oogenesis Hormonal Control of Female Sexual Cycles Hormonal Control of Fertility Fertilization, Pregnancy and Birth Twins Birth Contraception Chemical Methods Hormonal Control Methods Timing Method Barrier Methods Surgical Methods Termination of Pregnancy Changes in Sexual Function with Age

Overview This chapter begins with the mechanics of the process of meiosis. Encourage students to put this process in perspective when they think about a generalized life cycle. It is important that they see the relationship of meiosis to mitosis as they cover this material. A summary table of meiosis

included in the chapter allows students to review a concise overview of this process. It highlights those aspects of meiosis that related to the mechanics of the process and features that result in gametic variety. Following this section is one that deals with chromosomes and sex determination providing information on the roles played by autosomes and the sex chromosomes.

The next section provides us with the opportunity to examine the ways our sexuality influences us throughout life, starting with the effect of the sex-determining chromosomes before birth as they direct the formation of hormones that control the development of sex organs. With the start of puberty, renewed hormonal activity causes major structural and behavioral changes that influence us for the remainder of our lives. Since our sexuality is tied to reproduction, we consider the production of offspring next. Finally, we turn our attention to normal sexual activity in the aging individual. We have tried to include a discussion of many of the areas of concern for young people based on the questions we receive. As far as possible, we have attempted to place the emphasis on biological rather than sociological discussion. A dissection laboratory experience might be appropriate with this chapter. Such dissections will emphasize the anatomical structures of the reproductive system in various animals.

Boxed materials that illustrate the importance of sexual reproduction of the depth of our knowledge include: the concepts that explain the meiotic reasons why individuals differ, karyotyping and Down syndrome, and the human genome project.

For Class Discussions 1. Fertilization of the human egg normally occurs after the a. lining of the uterus is thicker and filled with blood. b. egg has started development in the follicle. c. menstrual flow (or period) has started. d. egg has imbedded itself in the wall of the uterus.

2. The time of menstrual flow, or period, in a normal human female occurs a. at the same time as the egg is released from the ovary. b. approximately two days before the egg is released from the ovary. c. approximately two days after the egg is released from the ovary. d. approximately two weeks after the egg is released from the ovary.

3. Which is not one of the five factors that influence genetic diversity in offspring? a. mutations b. crossing-over c. segregation d. hormone cycles

4. If a female is under 15 years of age or has had three or more pregnancies in a two-year period which is NOT true? a. nutritional stores are inadequate to support a successful pregnancy b. the use of ‗street‘ drugs ex. alcohol, can result in decreased nutrient exchange between the mother and fetus c. heavy smoking can result in low birth weights d. she will most likely have twins 5. Without this gene, the embryo would become female. a. SRY b. TDF c. X d. Turner‘s 6. An individual who has XXY chromosomes has the genetic condition is known as a. Klinefelter‘s syndrome b. Turner‘s syndrome c. Barr‘s syndrome d. Cryptorchidism 7. At puberty the hypothalamus begins to release a hormone known as gonadotropin-releasing hormone (GnRH), which stimulates the pituitary to release the hormones a. luteinizing hormone (LH) and follicle-stimulating hormone (FSH) b. oxytocin and follicle-stimulating hormone (FSH) c. estrogens and androgens d. testosterones and estrogens 8. Semen, or seminal fluid, is a mixture of sperm and secretions from three accessory glands.

Which is NOT an accessory gland? a. seminal vesicles b. prostate c. bulbo-urethral gland d. pituitary 9. Men must be able to release at least ____?___ sperm per milliliter to be fertile? a. 400,000 b. 100 million c. 400 million d. one each month

10. The follicle from which the oocyte erupted develops into a gland like structure called the a. corpus luteum b. seminal vesicle c. polar body d. epididymis 11. The lining of the uterus, the ___?___, is shed during menstruation, menstrual flow, or a period. a. epidermis b. endometrium c. epididymis d. hypothalamus 12. Which of the following is NOT a vitamin? a. Thiamine b. Riboflavin c. Niacin d. Calcium 13. In most women, a secondary oocyte is released from the ovary about ___?___ days before the next menstrual period. a. 2 b. 7 c. 14 d. 21 14. If a woman normally has a regular 21-day menstrual cycle, ovulation would occur about day ___?___ in the cycle. a. 7 b. 14 c. 21 d. 31 15. This division of embryonic cells is called a. meiosis b. mitosis c. cleavage d. both b and c above

16. Two other membranes, the chorion and allantois, fuse with the lining of the uterus to form the tructure known as the a. placenta b. yolk sac c. digestive system d. spinal cord 17. If during cleavage the embryo splits into two separate groups of cells, the result will be a. Siamese twins b. identical twins c. fraternal twins d. twins of different sexes

Answers: 1a, 2d, 3d, 4d, 5a, 6a, 7a, 8d, 9b, 10a, 11b, 12d, 13c, 14b, 15d, 16b. 17. b.

Answers to End of Chapter Concept Questions 1. Haploid cells do not have homologous chromosomes; diploid cells do.

2. Homologous chromosomes line up in pairs, not as individuals.

3.

Mitosis Meiosis 2 cells formed 4 cells formed Cells are identical to parent cell cells go from diploid to haploid No crossing over crossing over occurs No segregation segregation occurs Asexual reproduction used for sexual reproduction, sperm or egg 4. Rhythm method of conception control Advantages No chemical or mechanical methods used

Disadvantages Success rate very low Difficult to judge ‗safe period‘

The simplest and least expensive There may be only a few days each month for intercourse without the possibility of pregnancy 5. Have students check their illustrations in comparison to those in the text.

6. HRT stands for hormone replacement therapy. It may be used by women to augment the natural production of the hormones estrogen and progestin. HRT might have long-term benefits for women with osteoporosis and heart disease, but that it might increase the risk for breast cancer.

7.

Structure Ovary

Vagina

Function Production of eggs Production of hormones Conducts egg toward uterus Conducts sperm toward ovary Location of implanted embryo Contributes to formation of placenta Produces hormones Passageway from outside of body into uterus

8.

Structure Testis Vas deferens Seminal vesicle Prostate Bulbourethral gland Urethra Penis Scrotum

Function Produces sperm Sperm-conducting tubes Produces semen Produces semen Produces semen Sperm and urine-carrying tube Vascularized tube containing urethra Sac that contains testes outside body

9.

Oogenesis Spermatogenesis Occurs in females Occurs in males Results in one egg Results in four sperm Begins before birth Begins at puberty Single egg released per 28-day cycle Millions released with each ejaculation Large cell Small cell Nonmotile Motile

Oviduct Uterus

10. Ovulation and menstruation are two hormonally controlled cycles of the female reproductive system. The hormones regulate the ovulation cycle so that the ovary releases the egg on or about the fourteenth day of the cycle. At this point the lining of the uterus is thick and is prepared to accept a fertilized egg for implantation. If no such zygote is present, the lining of the uterus is sloughed off in the process called menses or flow. The building and sloughing off of the uterine wall is called the menstrual cycle.

11.

Fraternal twins are derived from the fertilization of two separate eggs by two different sperm. Identical twins are derived from a single fertilized egg that has begun to undergo cleavage and then separated into two different cell masses. Each of these masses then develops into an individual.

12.

Causes of infertility Males Females Male tube blockages Endometriosis Sperm problems Ovulation problems Sperm allergy Poor egg quality 13. Answer will vary. One possible response: An organism with two sets of chromosomes can produce many combinations of chromosomes when it produces sex cells leading to greater genetic diversity in subsequent generations.

14. Point mutations and chromosomal aberrations. In point mutations, a change in a DNA nucleotide results in the production of a different protein. In chromosomal aberrations, genes are rearranged when parts of chromosomes are duplicated, deleted, or inverted. By causing the production of different proteins, both types of mutations increase diversity.

15. During meiosis I, the number of chromosomes is reduced from the diploid number to the haploid number. Therefore, it is often referred to as a reduction division.

End of Chapter Group B Solutions 1.

Year 2000 – 6 billion humans Year 2040 – 12 billion humans Year 2080 – 24 billion humans Year 2120 – 48 billion humans Year 2160 – 96 billion humans Year 2200 – 192 billion humans

2. Percentage increase is the ratio of the change to the original amount





testosterone

14yr- old

- testostreone11yr- old 

testostreone11yr- old

 100%

750 ng / dl - 440 ng / dl  100% 440 ng / dl

 0.70  100%  70%

3. Percentage increase is the ratio of the change to the original amount 



estrogen

surge

- estrogen normal 

estrogen normal

 100%

50 pg / mL - 15 pg / mL  100% 15 pg / mL

 2.33  100%  233 %

4. If the amount reaching Fallopian tube is the total sperm times the rate, then Sperm reaching Fallopian tube

= total number of sperm × rate of reaching Fallopian

tube = 250 million sperm × 1 sperm/14 million sperm = 17.9 million sperm

26

Mendelian and Molecular Genetics

Contents Genetics, Meiosis, and Cells Single-Gene Inheritance Patterns A Simple Model of Inheritance - Dominant and Recessive Alleles Mendel‘s Laws of Heredity Steps in Solving Heredity Problems: Single-Factor Crosses More Complex Models of Inheritance X-Linked Genes Codominance Incomplete Dominance Multiple Alleles Polygenic Inheritance Pleiotropy Environmental Influences on Gene Expression Epigenetics and Gene Expression Molecular Basis of Genetics The Structure of DNA and RNA DNA Replication DNA Transcription Translation or Protein Synthesis Alterations of DNA Using DNA to OUR Advantage Strategy One: Genetic Modification of Organisms Strategy Two: Sequencing

Overview The first part of this concluding chapter introduces the concepts of single-gene inheritance patterns and terminology that will be used in specific contexts later on in the chapter: alleles, genotype, phenotype, homologous chromosomes, heterozygous, dominant, recessive and codominant. The typical shorthand notation used in genetics is also introduced. The section ends with a consideration of alternative inheritance genetics including lack of dominance, multiple alleles, polygenic inheritance, pleiotropy, sex-linked characteristics, and the influence of the environment on the expression of genes.

We designed this chapter to introduce the student to a difficult subject. A great deal of effort, therefore, has gone into relating the concepts of protein synthesis, chemical codes of

DNA, and the cell life cycle in a manner that will allow the student who is totally unfamiliar with such material to grasp the information. The biggest difficulty in attempting to compare these types of materials is that students may lose sight of how the concepts relate to the total metabolism of the cell. It would be valuable to link the cellular processes of mitosis and meiosis with DNA replication and protein synthesis as the mean by which a cell expresses a phenotype.

For Class Discussions 1. In humans, the genes for blood type A and B show lack of dominance and both dominate O. Two type O people would be able to have a. 1 O: 1 A: 1 B: 1 AB type children. b. only O type children. c. 1 O: 1 A type children. d. only AB type children.

2.

Which is a group of proteins resulting from protein synthesis? a. structural b. carrier c. enzymatic/hormonal d. All the above are categories

3. Which of the following represents the sex chromosomes in a typical human female? a. XY b. XXX c. XO d. XX 4. The Y chromosome is carried in the a. egg. b. egg or sperm. c. polar body. d. sperm.

5. If a sperm containing an X chromosome fertilizes an egg, the child will be a. a girl. b. a boy. c. twins, a boy and a girl. d. twin boys.

6. Which one of the following does not express one of Mendel‘s laws? a. When two different alleles are present for a given trait, the expression of one will mask the expression of the other. b. Alleles separate during the formation of sex cells. c. During the formation of sex cells, members of one gene pair separate from one another independently of members of other gene pairs. d. Genes located on the same chromosome have a greater tendency of being inherited together than do genes located on different chromosomes.

7.

Which best represents the central dogma? a.

DNA (replication)  DNA  (transcription)  RNA  (translation)  Proteins b.

RNA (replication)  RNA  (transcription)  RNA  (translation)  Proteins c.

DNA (replication)  DNA  (transduction)  RNA  (transcription)  Proteins d.

Proteins (replication)  DNA  (transcription)  RNA  (translation)  Proteins

8. If an individual has the genotype BbCc, how many different kinds of gametes can that individual produce? a. one b. two c. three d. four 9. A nucleotide is composed of the following molecules arranged in this order: a. three amino acids covalently bonded in a series. b. three fatty acids individually bonded to three different places on glycerol. c. a base bonded to a sugar bonded to a phosphate. d. mRNA bonded to tRNA bonded to an amino acid.

10. Which of the following best describes the structure of DNA? a. single helix

b. protein coil c. double helix d. globular RNA 11. DNA is a. a single chain of nucleotides containing deoxyribose. b. mainly found in the cytoplasm. c. composed of amino acids. d. a coiled double chain of nucleotides.

12. In DNA replication, a. a new cover is made for the gene. b. a new gene is made for the cover. c. Both of these occur. d. None of these occur.

13. ―Since every cell in this patient‘s body has the same genetic pattern, it is likely that…‖ a. he acquired this pattern from one of his parents. b. he was exposed to mutagenic agents. c. his mother was the only source of the mutant gene. d. All the above are true.

14. The term ―recombinant DNA technology‖ refers to a. deliberately moving genes from one type of cell into another so that the new cell synthesizes that specific gene product b. selective breeding c. ensuring that a specific gene will be replicated over-and-over d. synthesizing DNA from scratch

Answers: 1b, 2d, 3d, 4d, 5a, 6d, 7a, 8d, 9c, 10c, 11d, 12c, 13a, 14a.

Answers to End of Chapter Concept Questions 1.

2.

Parents AA  aa Aa  Aa Aa  Aa AA  aa

Offspring Aa Aa aa or Aa  Aa or Aa  aa

Probability 100% 50% 25%

3.

a.

1/4 or 25% b.

2/3 or 67% 4. Since both parents do not display achondroplasia, it must be assumed that the child is the result of a new mutation in one of the parents.

5. a. (4) All the girls have the normal phenotype but are carriers. b.

(6) All the boys are color- deficient.

6.

Father XNY Mother XnXN Mother‘s father XNY Mother‘s mother XNXn Father‘s father XNY? Father‘s mother XNX? 7. The alleles responsible for color are neither dominant nor recessive to one another, and both express themselves in the heterozygous individual.

8. DNA—A polymer of nucleotides that serves a genetic information source. In prokaryotic cells, it is duplex DNA (double-stranded) and contains no permanently attached proteins. In eukaryotic cells, it is in strands with attached histone proteins. When tightly coiled, it is known as a chromosome.

RNA—A polymer of nucleotides that form on the template surface of DNA by transcription.

Three forms have been identified: mRNA, rRNA, and tRNA. 9. Protein synthesis = transcription + translation. DNA chemical code opens with the aide of an enzyme; individual mRNA nucleotide units base-pair with exposed DNA nucleotides; and an mRNA molecule forms a single strand using DNA as a template. mRNA leaves DNA, and DNA reforms as a double helix; mRNA moves from the nucleus into the cytoplasm where tRNA molecules carrying specific amino acids move to the ribosome and base-pair with mRNA codons. Aligned amino acids combine in a sequence determined by codons of mRNA into a specific protein. mRNA leaves the ribosome, and tRNA molecules leave the ribosome without amino acids. The completed protein leaves the ribosome.

10. Chromosomal mutation is a change in the gene arrangement in a cell that is usually the result of a break in the DNA. A point mutation is a change in the nitrogenous base sequence of a DNA molecule. Recombinant DNA is an altered form created in a laboratory by manipulating genes.

11. DNA replication involves the alignment of DNA nucleotides on both strands of the DNA molecule; RNA production involves the same process. RNA nucleotides are aligned, however, only on the sequence of nucleotides that serve as the chemical code for proteins.

12. DNA—CATAAAGCA; mRNA—GUAUUUCGU. 13. Amino acid sequence—alanine, phenylalanine, arginine.

14. The production of customized stem cell lines. In this application a somatic cell from a patient would be inserted into a human egg from which the nucleus has been removed. The egg would divide and generate stem cells. These cells could then be cultured and used for therapy. In this example the stem cells could be used to create pancreatic cells to treat a diabetic patient.

15. The enzyme DNA polymerase moves in opposite directions on each side down the length of DNA, attaching new DNA nucleotides into position during DNA replication. Relatively weak hydrogen bonds hold each in position (AT, GC), while the new nucleotide is bonded to its neighboring nucleotide more strongly with covalent bonds between the sugar and phosphate of the new backbone.

16. The ―guardian of the genome,‖ or the tumor-suppressor gene.

17. Cell death that has a genetic basis and is not the result of injury.

18. Benzopyrene is a carcinogen, i.e., cancer causing agent. For decades cancer has been empirically (based on commonplace experiences) linked to the use of tobacco, but only recently have researchers showed a cause-and-effect relationship between the two. Studies of patients with lung cancer revealed that 60 percent exhibited mutations in a gene known as p53. This gene is responsible for the synthesis of a protein that keeps cells growing in a controlled fashion and, when necessary, causes cells to commit suicide, a process called apoptosis. To be more specific, one of the compounds in tobacco (benzo[a]pyrene) has the ability to attach and mutate three spots in this gene, the same spots where the p53 genes have been changed in lung cancer patients.

Studies of this nature give strong scientific evidence that smoking causes lung cancer.

19. When p53 initiates apoptosis in cancer cells, the cell‘s DNA is cut into pieces and the cytoplasm and nucleus shrink. This is followed by its engulfment by phagocytes. In this manner, cells that are potentially dangerous to the entire body (tumor cells) are killed before they cause serious harm.

20. It is known that the difference between the genomes of humans and chimpanzees is about 1.5%. If this there is only this small difference between what appears to be two strikingly different organisms, a. What percentage difference do you think exists among humans? Ans: Will vary. b. Based on this information, comment on the validity of separating humans of the world in to separate races. Answers will vary.

End of Chapter Group B Solutions 1.

percentage of adenine = 28% percentage of adenine must equal percentage of quanine percentage of adenine and percentage of quanine = 56% percentage of thymine and percentage of cytosine percentage of cytosine = 22%

2.

bacteria at beginning = 100 thousand bacteria at 1 minute = 400 thousand bacteria at 2 minutes = 16 million

bacteria at 3 minutes = 64 million bacteria at 4 minutes = 256 million bacteria at 5 minutes = 1024 million

3.

number of mutant bacteria

= total bacteria × rate of mutation = 1024 million × 1 mutant/1 million bacteria = 1024 mutant bacteria

4. B+ carriers = population × percentage of carriers = 19.4 million × 25% = 4.9 million