Test Bank for Physics, 12th Edition John D. Cutnell, Kenneth W. Johnson, David Young, Shane Stadler Chapter 1-32
Chapter: Chapter 1 Multiple Choice
1. Which one of the following is an SI base unit? A) gram B) slug C) newton D) centimeter E) kilogram Ans: E Difficulty: Easy SectionDef: Section 1-2 and Section 1-3
2. Complete the following statement: Today, the standard meter is defined in terms of A) the distance from the earth's equator to the north pole. B) the wavelength of light emitted from a krypton atom. C) the wavelength of light emitted from a sodium atom. D) a platinum-iridium bar kept in France. E) the speed of light. Ans: E Difficulty: Medium SectionDef: Section 1-2 and Section 1-3
3. Complete the following statement: Today, the standard unit of mass is defined in terms of A) a specified volume of water at 4 °C. B) Planck’s constant h. C) a specified number of cesium atoms. D) a standard platinum bar. E) the speed of light.
Ans: B
Difficulty: Medium SectionDef: Section 1-2 and Section 1-3
4. Complete the following statement: Today, the standard unit of time is defined in terms of A) the electromagnetic waves emitted by cesium atoms. B) the motion of the moon around the earth. C) the motion of a precision pendulum. D) the average solar day. E) the speed of light. Ans: A Difficulty: Medium SectionDef: Section 1-2 and Section 1-3
5. The mass of a raindrop is 4 milligrams. Which one of the following statements indicates the correct mass of the raindrop in grams? A) The raindrop has a mass of 4 × 106 grams. B) The raindrop has a mass of 4 × 10–3 grams. C) The raindrop has a mass of 4 × 10–1 grams. D) The raindrop has a mass of 4 × 103 grams. E) The raindrop has a mass of 4 × 10–6 grams. Ans: B Difficulty: Medium SectionDef: Section 1-2 and Section 1-3
6. Which one of the following is the longest length? A) 100 meters B) 102 centimeters C) 104 millimeters D) 105 micrometers E) 107 nanometers Ans: C
Difficulty: Medium SectionDef: Section 1-2 and Section 1-3
7. In a diving competition, a woman dives from a platform that is ten meters above the surface of the water. What is the height, expressed in feet, of the platform? A) 13 feet B) 18 feet C) 24 feet D) 33 feet E) 47 feet Ans: D Difficulty: Medium SectionDef: Section 1-2 and Section 1-3
8. A candy shop sells a pound of chocolate for $ 10.85. What is the price of 1.50 kg of chocolate at the shop? A) $ 8.17 B) $ 13.49 C) $ 17.98 D) $ 29.73 E) $ 35.81 Ans: E Difficulty: Hard SectionDef: Section 1-2 and Section 1-3
1 milligram 9. Complete the following statement: The ratio 1 kilogram is equal to
A) 102. B) 103. C) 106. D) 10–3. E) 10–6. Ans: E Difficulty: Medium
SectionDef: Section 1-2 and Section 1-3
10. Which one of the following choices is equivalent to 8.0 m2? A) 8.0 × 10–4 cm2 B) 8.0 × 102 cm2 C) 8.0 × 10–2 cm2 D) 8.0 × 104 cm2 E) 8.0 × 103 cm2 Ans: D Difficulty: Hard SectionDef: Section 1-2 and Section 1-3
11. Which one of the following pairs of units may not be added together, even after the appropriate unit conversions have been made? A) grams and milligrams B) kilometers and kilograms C) miles and kilometers D) slugs and kilograms E) centimeters and yards Ans: B Difficulty: Easy SectionDef: Section 1-2 and Section 1-3
12. Which one of the following choices is equivalent to 44.5 mm? A) 4.45 × 101 m B) 4.45 × 10–2 m C) 44.5 × 10–1 m D) 44.5 × 10–2 m E) 4.45 × 100 m Ans: B Difficulty: Medium SectionDef: Section 1-2 and Section 1-3
13. Which one of the following choices is equivalent to 152 m? A) 1.52 × 101 m B) 1.52 × 102 m C) 1.52 × 10–1 m D) 1.52 × 10–2 m E) 1.52 × 100 m Ans: B Difficulty: Easy SectionDef: Section 1-2 and Section 1-3
14. In the sport of horseshoe pitching, two stakes are 40.0 feet apart. What is the distance in meters between the two stakes? A) 24.4 m B) 4.80 m C) 18.3 m D) 12.2 m E) 15.7 m Ans: D Difficulty: Medium SectionDef: Section 1-2 and Section 1-3
15. The Boston Marathon is the oldest annual foot race, in which those that finish complete a distance of 26 miles, 385 yards. Express this distance in kilometers. A) 16.295 km B) 16.398 km C) 42.193km D) 42.453 km E) 56.496 km Ans: C Difficulty: Medium SectionDef: Section 1-2 and Section 1-3
16. The surface of a lake has an area of 15.5 km2. What is the area of the lake in m2? A) 1.55 × 104 m2 B) 1.55 × 105 m2 C) 1.55 × 106 m2 D) 1.55 × 107 m2 E) 1.55 × 108 m2 Ans: D Difficulty: Hard SectionDef: Section 1-2 and Section 1-3
a
b2 c . If the
17. The mathematical relationship between three physical quantities is given by [L] dimension of b is; [T] and the dimension of c is [L]. Which one of the following choices is the dimension of a? A) [L] [L] 2 B) [T]
[L] C) [T] D) [T] [L]2 2 E) [T]
Ans: B Difficulty: Medium SectionDef: Section 1-2 and Section 1-3
18. The distance d that a certain particle moves may be calculated from the expression d = at + bt2 where a and b are constants; and t is the elapsed time. What must the dimensions of the quantities a and b be, respectively?
[L] [L] , 2 [T] [T] A)
B) [L], [L]2 [L] [L] , 3 2 C) [T] [T]
[L] [L]2 , 2 [T] [T] D) 1 1 , 2 E) [T] [T]
Ans: A Difficulty: Medium SectionDef: Section 1-2 and Section 1-3
19. Using the dimensions given for the variables in the table, determine which one of the following expressions is correct.
f
A)
variable f
dimension 1 [T]
l
[L]
g
[L] [T]2
g 2 l
B) f = 2gl
2 f C)
g l
2 f
D) E)
l g
f 2 gl
Ans: C Difficulty: Hard SectionDef: Section 1-2 and Section 1-3
20. A certain physical quantity, R, is calculated using the formula: R = 4a2(b – c) where a, b, and c are distances. What is the SI unit for R? A) cm B) cm2 C) m D) m2 E) m3 Ans: E Difficulty: Medium SectionDef: Section 1-2 and Section 1-3
21. Which one of the following expressions may be used to correctly find the angle in the drawing?
5
A)
cos 1 2
B)
tan 1 2
5
2
C)
sin 1 5
D)
tan 1 5
E)
sin 1 2
2
5
Ans: B Difficulty: Easy SectionDef: Section 1-4
22. The length of each side of a square is 4.0 m. What is the length of the diagonal of the square (shown as a dashed line in the figure)?
A) 2.8 m B) 8.0 m C) 5.7 m D) 6.8 m E) 16 m Ans: D Difficulty: Medium SectionDef: Section 1-4
23. Three sticks are arranged to form a right triangle. If the lengths of the three sticks are 0.47 m, 0.62 m and 0.78 m, what are the three angles of the triangle? A) 90°, 45°, and 45° B) 90°, 62°, and 28° C) 90°, 59°, and 31° D) 90°, 48°, and 42° E) 90°, 53°, and 37° Ans: E Difficulty: Medium SectionDef: Section 1-4
24. A 3.0-m ladder leans against a wall and makes an angle with the wall of 28° as shown in the drawing. What is the height h above the ground where the ladder makes contact with the wall?
A) 2.6 m B) 2.3 m C) 2.1 m D) 1.9 m E) 1.6 m Ans: A Difficulty: Medium SectionDef: Section 1-4
25. A pole is held vertically by attaching wires at a height of 13.4 m above the ground. The other end of each wire is anchored in the ground at a distance of 9.54 m from the base of the pole. The pole makes a right angle with the ground. What is the length of each wire? A) 14.1 m B) 19.7 m C) 11.5 m D) 16.4 m E) 22.8 m Ans: D Difficulty: Hard SectionDef: Section 1-4
26. A certain mountain road is inclined 3.1° with respect to the horizon. What is the change in altitude of the car as a result of its traveling 2.90 km along the road? A) 157 m B) 181 m
C) 116 m D) 203 m E) 289 m Ans: A Difficulty: Hard SectionDef: Section 1-4
27. A surveyor wants to find the shortest distance across a section of river. A stake is placed on each bank of the river as shown in the figure. She measures a distance of 30.0 m from one stake to another on the same side of the river, thus finding the third leg on a right triangle. She then measures the angle and finds it equal to 75.9°. What is the shortest distance across this section of river?
A) 89.2 m B) 15.3 m C) 119 m D) 268 m E) 29.0 m Ans: C
Difficulty: Medium SectionDef: Section 1-4
28. Which one of the following choices is a vector quantity? A) mass B) temperature C) time D) displacement E) volume
Ans: D Difficulty: Easy SectionDef: Section 1-5
29. Which one of the following quantities is a vector quantity? A) the age of the earth B) the mass of a freight train C) the earth's pull on your body D) the temperature of an iced coffee E) the number of people attending a soccer game Ans: C Difficulty: Medium SectionDef: Section 1-5
30. Which one of the following statements is true concerning scalar quantities? A) Scalar quantities must be represented by base units. B) Scalar quantities have both magnitude and direction. C) Scalar quantities can be added to vector quantities using rules of trigonometry. D) Scalar quantities can be added to other scalar quantities using rules of trigonometry. E) Scalar quantities can be added to other scalar quantities using rules of ordinary addition. Ans: E Difficulty: Medium SectionDef: Section 1-5
31. Two vectors A and B are added together to form a vector C . The relationship between the magnitudes of the vectors is given by A + B = C. Which one of the following statements concerning these vectors is true? A) A and B must be displacements. B) A and B must have equal lengths. C) A and B must point in opposite directions. D) A and B must point in the same direction. E) A and B must be at right angles to each other.
Ans: D Difficulty: Hard SectionDef: Section 1-5 and 1-6
32. Two vectors A and B are added together to form a vector C . The relationship between the magnitudes of the vectors is given by: A2 + B2 = C2. Which statement concerning these vectors is true? Note that A and B are not the zero vector. A) A and B must be at right angles to each other. B) A and B could have any orientation relative to each other. C) A and B must have equal lengths. D) A and B must be parallel. E) A and B could be antiparallel. Ans: A
Difficulty: Medium SectionDef: Section 1-5 and 1-6
33. Three vectors A , B , and C add together to yield zero: A + B + C = 0. The vectors A and C point in opposite directions and their magnitudes are related by the expression: A = 2C. Which one of the following conclusions is correct? A) A and B have equal magnitudes and point in opposite directions. B) B and C have equal magnitudes and point in the same direction. C) B and C have equal magnitudes and point in opposite directions. D) A and B point in the same direction, but A has twice the magnitude of B . E) B and C point in the same direction, but C has twice the magnitude of B . Ans: B Difficulty: Hard SectionDef: Section 1-5 and 1-6
34. What is the angle between the vectors A and – A when they are drawn from a common origin? A) 0° B) 90° C) 180° D) 270° E) 360° Ans: C Difficulty: Easy SectionDef: Section 1-5 and 1-6
35. What is the minimum number of vectors with unequal magnitudes whose vector sum can be zero? A) two B) three C) four D) five E) six Ans: B Difficulty: Medium SectionDef: Section 1-5 and 1-6
36. What is the minimum number of vectors with equal magnitudes whose vector sum can be zero? A) two B) three C) four D) five E) six Ans: A Difficulty: Easy SectionDef: Section 1-5 and 1-6
37. A physics student adds two displacement vectors with magnitudes of 8.0 km and 6.0 km. Which one of the following statements is true concerning the magnitude of the resultant displacement? A) It must be 10.0 km. B) It must be 14.0 km. C) It could be equal to zero kilometers, depending on how the vectors are oriented. D) No conclusion can be reached without knowing the directions of the vectors. E) It could have any value between 2.0 km and 14.0 km depending on how the vectors are oriented. Ans: E Difficulty: Medium SectionDef: Section 1-5 and 1-6
38. A student adds two displacement vectors with magnitudes of 6.0 m and 8.0 m, respectively. Which one of the following could not be a possible choice for the resultant? A) 2.3 m B) 6.6 m C) 10.0 m D) 12.8 m E) 14.8 m Ans: E Difficulty: Medium SectionDef: Section 1-5 and 1-6
39. Two displacement vectors of magnitudes 21 cm and 79 cm are added. Which one of the following is the only possible choice for the magnitude of the resultant? A) 0 cm B) 28 cm C) 37 cm D) 82 cm E) 114 cm Ans: D Difficulty: Hard SectionDef: Section 1-5 and 1-6
40. Which expression is false concerning the vectors shown in the sketch?
A) C = A + B B) C + A = – B C) A + B + C = 0 D) C < A + B E) A 2 + B 2 = C 2 Ans: A Difficulty: Hard SectionDef: Section 1-5 and 1-6
41. City A lies 30 km directly south of city B. A bus, beginning at city A travels 50 km at 37° north of east to reach city C. How far and in what direction must the bus go from city C to reach city B? A) 20 km, west B) 40 km, west C) 80 km, west D) 40 km, east E) 80 km, east Ans: B Difficulty: Medium SectionDef: Section 1-5 and 1-6
42. Town A lies 20 km north of town B. Town C lies 13 km west of town A. A small plane flies directly from town B to town C. What is the displacement of the plane? A) 33 km, 33° north of west B) 19 km, 33° north of west C) 24 km, 57° north of west D) 31 km, 57° north of west E) 6.6 km, 40° north of west
Ans: C Difficulty: Medium SectionDef: Section 1-5 and 1-6
43. A runaway dog walks 0.64 km due north. He then runs due west to a hot dog stand. If the magnitude of the dog's total displacement vector is 0.91 km, what is the magnitude of the dog's displacement vector in the due west direction? A) 0.27 km B) 0.33 km C) 0.41 km D) 0.52 km E) 0.65 km Ans: E Difficulty: Medium SectionDef: Section 1-5 and 1-6
44. An escaped convict runs 1.70 km due east of the prison. He then runs due north to a friend's house. If the magnitude of the convict's total displacement vector is 2.50 km, what is the direction of his total displacement vector with respect to due east? A) 43° south of east B) 47° north of east C) 56° north of east D) 34° south of east E) 34° north of east Ans: B Difficulty: Medium SectionDef: Section 1-5 and 1-6
45. Four members of the Main Street Bicycle Club meet at a certain intersection on Main Street. The members then start from the same location, but travel in different directions. A short time later, displacement vectors for the four members are: A = 2.0 km, east; B = 5.2 km, north; C = 4.9 km, west; D = 3.0 km, south What is the resultant displacement R of the members of the bicycle club: R = A + B + C + D?
A) 0.8 km, south B) 0.4 km, 45° south of east C) 3.6 km, 37° north of west D) 4.0 km, east E) 4.0 km, south Ans: C Difficulty: Hard SectionDef: Section 1-5 and 1-6
46. A force, F1 , of magnitude 2.0 N and directed due east is exerted on an object. A second force exerted on the object is F 2 = 2.0 N, due north. What is the magnitude and direction of a third force, F3 , which must be exerted on the object so that the resultant force is zero? A) 1.4 N, 45° north of east B) 1.4 N, 45° south of west C) 2.8 N, 45° north of east D) 2.8 N, 45° south of west E) 4.0 N, 45° east of north Ans: D Difficulty: Hard SectionDef: Section 1-5 and 1-6
47. A sailboat leaves a harbor and sails 1.8 km in the direction 65° south of east, where the captain stops for lunch. A short time later, the boat sails 1.1 km in the direction 15° north of east. What is the magnitude of the resultant displacement from the harbor? A) 2.3 km B) 1.5 km C) 2.9 km D) 1.2 km E) 0.59 km Ans: A Difficulty: Hard SectionDef: Section 1-6 and 1-7
48. Three vectors A , B , and C have the following x and y components:
Ax = 1 m, Ay = 0 m, Bx = 1 m, By = 1 m, Cx = 0 m, Cy = –1 m According to the graph, how are A , B , and C combined to result in the vector D ?
A) D = A – B – C B) D = A – B + C C) D = A + B – C D) D = A + B + C E) D = – A + B + C Ans: C Difficulty: Medium SectionDef: Section 1-5 and 1-6
49. A displacement vector has a magnitude of 810 m and points at an angle of 18° above the positive x axis. What are the x and y scalar components of this vector? x scalar component y scalar component A) 770 m 250 m B) 560 m 585 m C) 585 m 560 m D) 250 m 750 m E) 713 m 385 m Ans: A Difficulty: Easy SectionDef: Section 1-7
50. Which one of the following statements concerning vectors and scalars is false? A) In calculations, the vector components of a vector may be used in place of the vector itself. B) It is possible to use vector components that are not perpendicular. C) A scalar component may be either positive or negative.
D) A vector that is zero may have components other than zero. E) Two vectors are equal only if they have the same magnitude and direction. Ans: D Difficulty: Medium SectionDef: Section 1-7
51. A displacement vector is 23 km in length and directed 65° south of east. What are the components of this vector? Eastward Component Southward Component A) 21 km 9.7 km B) 23 km 23 km C) 23 km 0 km D) 9.7 km 21 km E) 0 km 23 km Ans: D Difficulty: Easy SectionDef: Section 1-7
52. The x and y components of a displacement vector are –3.00 m and +4.00 m, respectively. What angle does this vector make with the positive x axis? A) 233° B) 127° C) –53.0° D) 53.0° E) 37.0° Ans: B Difficulty: Medium SectionDef: Section 1-7
53. A race car will make one lap around a circular track of radius R. When the car has traveled halfway around the track, what is the magnitude of the car's displacement from the starting point? A) 2R B) R
C) R D) 2R E) zero meters Ans: A Difficulty: Medium SectionDef: Section 1-7
54. A bug crawls 2.25 m along the base of a wall. Upon reaching a corner, the bug's direction of travel changes from south to west. The bug then crawls 3.15 m before stopping. What is the magnitude of the bug's displacement? A) 5.40 m B) 2.72 m C) 3.87 m D) 4.11 m E) 3.29 m Ans: C Difficulty: Medium SectionDef: Section 1-5 and 1-6
55. During the execution of a play, a football player carries the ball for a distance of 33 m in the direction 58° north of east. To determine the number of meters gained on the play, find the northward component of the ball's displacement. A) 8.0 m B) 16 m C) 24 m D) 28 m E) 32 m Ans: D Difficulty: Easy SectionDef: Section 1-7
56. A bird flies 25.0 m in the direction 55° east of south to its nest on a cliff. The bird then flies 75.0 m in the direction 55° west of north to the top of a tree. What are the northward and westward components of the resultant displacement of the bird from its nest?
northward westward A) 29 m 41 m B) 41 m 29 m C) 35 m 35 m D) 81 m 57 m E) 57 m 81 m Ans: A Difficulty: Hard SectionDef: Section 1-7
57. Use the component method of vector addition to find the resultant of the following three vectors: A = 56 km, east
B = 11 km, 22° south of east C = 88 km, 44° west of south A) 81 km, 14° west of south B) 97 km, 62° south of east C) 52 km, 66° south of east D) 68 km, 86° south of east E) 66 km, 7.1° west of south
Ans: D Difficulty: Medium SectionDef: Section 1-8
58. Use the component method of vector addition to find the components of the resultant of the four displacements shown in the figure. The magnitudes of the displacements are: A = 2.25 cm, B = 6.35 cm, C = 5.47 cm, and D = 4.19 cm.
x component y component A) 2.19 cm –6.92 cm B) 3.71 cm –1.09 cm C) 5.45 cm –2.82 cm D) 1.09 cm –3.71 cm E) 6.93 cm –2.19 cm Ans: E Difficulty: Easy SectionDef: Section 1-8
59. A vector F1 has a magnitude of 40.0 units and points 35.0° above the positive x axis. A second vector F 2 has a magnitude of 65.0 units and points in the negative x direction. Use the component method of vector addition to find the magnitude and direction, relative to the positive x axis, of the resultant F = F1 + F 2 . A) 53.3 units, 141.8° relative to the +x axis B) 53.3 units, 52.1° relative to the +x axis C) 39.6 units, 144.6° relative to the +x axis D) 39.6 units, 54.6° relative to the +x axis E) 46.2 units, 136.0° relative to the +x axis Ans: C Difficulty: Medium SectionDef: Section 1-8
60. Two vectors A and B , are added together to form the vector C = A + B . The relationship between the magnitudes of these vectors is given by: Cx = A cos 30° + B and Cy = – A sin 30°. Which statement best describes the orientation of these vectors? A) A points in the negative x direction while B points in the positive y direction. B) A points in the negative y direction while B points in the positive x direction. C) A points 30° below the positive x axis while B points in the positive x direction. D) A points 30° above the positive x axis while B points in the positive x direction. E) A points 30° above the negative x axis while B points in the positive x direction. Ans: C Difficulty: Hard
SectionDef: Section 1-8
61. Which one of the following answers would give the correct number of significant figures when the following masses are added together: 3.6 kg, 113 kg, and 4.19 kg? A) 121 kg B) 120.8 kg C) 120.79 kg D) 1.20 × 102 kg E) 120.8 × 103 kg Ans: A Difficulty: Easy SectionDef: Additional Problems
62. A physics text has 544 sheets (1088 pages) and is 34.3 millimeters thick between the inside front cover and the inside back cover. What is the thickness of a single sheet? A) 6.36 × 10–4 m B) 3.16 × 10–2 m C) 6.28 × 10–3 m D) 7.24 × 10–6 m E) 6.31 × 10–5 m Ans: E Difficulty: Easy SectionDef: Additional Problems
63. Justine and her friends exit the physics classroom and walk 0.70 km to their math class. While walking, Justine's average step length is 58 cm. Approximately, how many steps does she take in walking between these two classes? A) 310 B) 720 C) 1200 D) 3100 E) 7200 Ans: C Difficulty: Medium
SectionDef: Additional Problems
Reference: Ref 1-1 Two vectors, A and B , are added together to form the vector C = A + B . The relationship between the magnitudes of these vectors is given by: Cx = 0 Cy = A sin 60° + B sin 30° Ax and Ay point in the positive x and y directions, respectively.
64. Which one of the following statements best describes the orientation of vectors A and B ? A) A and B point in opposite directions. B) A points 60° above the positive x axis while B points 30° above the negative x axis. C) A points 60° above the negative x axis while B points 30° above the positive x axis. D) A points 60° below the positive x axis while B points 30° above the positive y axis. E) A points 60° below the positive x axis while B points 30° below the positive y axis. Ans: B Refer To: Ref 1-1 Difficulty: Hard SectionDef: Additional Problems
65. How does the magnitude of A compare with that of B ? A) A = B B) A = 1.7B C) A = 0.4B D) A = 0.5B E) A = 0.7B Ans: B Refer To: Ref 1-1 Difficulty: Hard SectionDef: Additional Problems
Reference: Ref 1-2 The table gives the x and y components of two vectors A and B : Vector
A B
x component +15 units +15 units
y component +10 units –10 units
66. Which one of the following statements concerning these vectors is true? A) The vector A – B has no x component. B) The two vectors have different magnitudes. C) A makes a 56° angle with the positive x axis. D) B makes a 34° angle with the positive y axis. E) The vector A + B makes a 34° angle with the positive x axis. Ans: A Refer To: Ref 1-2 Difficulty: Medium SectionDef: Additional Problems
67. Determine the magnitude of the vector sum, A + B . A) 5 units B) 15 units C) 20 units D) 30 units E) 50 units Ans: D Refer To: Ref 1-2 Difficulty: Medium SectionDef: Additional Problems
68. Determine the magnitude of the vector difference, A – B . A) 5 units B) 15 units C) 20 units D) 30 units E) 50 units Ans: C Refer To: Ref 1-2 Difficulty: Medium SectionDef: Additional Problems
Reference: Ref 1-3 A boat radioed a distress call to a Coast Guard station. At the time of the call, a vector A from the station to the boat had a magnitude of 45.0 km and was directed 15.0° east of north. A vector from the station to the point where the boat was later found is B = 30.0 km, 15.0° north of east.
69. What are the components of the vector from the point where the distress call was made to the point where the boat was found? In other words, what are the components of vector C = B – A? x component y component A) 35.7 km, west 17.4 km, north B) 40.6 km, east 51.2 km, south C) 17.3 km, west 51.2 km, south D) 40.6 km, east 35.7 km, north E) 17.3 km, east 35.7 km, south Ans: E Refer To: Ref 1-3 Difficulty: Hard SectionDef: Additional Problems
70. How far did the boat travel from the point where the distress call was made to the point where the boat was found?
In other words, what is the magnitude of vector C ? A) 65.3 km B) 39.7 km C) 26.5 km D) 54.0 km E) 42.5 km Ans: B Refer To: Ref 1-3 Difficulty: Medium SectionDef: Additional Problems
Import Settings: Base Settings: Brownstone Default Information Field: Difficulty Information Field: SectionDef Highest Answer Letter: E Multiple Keywords in Same Paragraph: No
Chapter: Chapter 2
Multiple Choice
1. A particle travels along a curved path between two points P and Q as shown. The displacement of the particle does not depend on
35. An arrow is shot horizontally from a height of 4.9 m above the ground. The initial speed of the arrow is 45 m/s. Neglecting friction, how long will it take the arrow to hit the ground? A) 9.2 s B) 6.0 s C) 1.0 s D) 1.4 s E) 4.6 s Ans: C Difficulty: Medium SectionDef: Section 3-2 and Section 3-3
36. A cannonball at ground level is aimed 30.0° above the horizontal and is fired with an initial speed of 125 m/s. How far away from the cannon will the cannonball hit the ground? A) 125 m B) 138 m C) 695 m D) 1040 m E) 1380 m Ans: E Difficulty: Medium SectionDef: Section 3-2 and Section 3-3
37. A basketball is launched with an initial speed of 8.0 m/s and follows the trajectory shown. The ball enters the basket 0.96 s after it is launched. What are the distances x and y? Note: The drawing is not to scale.
x A) B) C) D)
y 5.4 m 7.7 m 5.4 m 5.7 m
0.73 m 0.91 m 0.91 m 0.73 m
E) 5.4 m
5.4 m
Ans: C Difficulty: Medium SectionDef: Section 3-2 and Section 3-3
38. A puck slides across a smooth, level tabletop at height H at a constant speed vo. It slides off the edge of the table and hits the floor a distance x away as shown in the figure.
What is the relationship between the distances x and H? 2H x v0 g A)
v02 x 2 gH B) x C)
v02 gH
H v0
D) x v0
E)
2x g
H g
Ans: A Difficulty: Hard SectionDef: Section 3-2 and Section 3-3
39. A bullet is aimed at a target on the wall a distance L away from the firing position. Because of gravity, the bullet strikes the wall a distance y below the mark as suggested in the figure. Note: The drawing is not to scale.
If the distance L was half as large and the bullet had the same initial velocity, how would y be affected? A) y will double. B) y will be half as large. C) y will be four times larger. D) y will be one fourth as large. E) y is not possible to determine unless numerical values are given for the distances. Ans: D Difficulty: Easy SectionDef: Section 3-2 and Section 3-3
Reference: Ref 3-6 A tennis ball is thrown upward at an angle from point A. It follows a parabolic trajectory and hits the ground at point D. At the instant shown, the ball is at point B. Point C represents the highest position of the ball above the ground.
40. While in flight, how do the x and y components of the velocity vector of the ball compare at the points B and C? A) The velocity components are non-zero at B and zero at C. B) The x components are the same; the y component at C is zero m/s. C) The x components are the same; the y component has a larger magnitude at C than at B. D) The x component is larger at C than at B; the y component at B points up while at C, it points downward. E) The x component is larger at B than at C; the y component at B points down while at C, it
points upward. Ans: B Refer To: Ref 3-6 Difficulty: Medium SectionDef: Section 3-2 and Section 3-3
41. While in flight, how do the x and y components of the velocity vector of the ball compare at the points A and D? A) The velocity components are non-zero at A and are zero m/s at D. B) The velocity components are the same in magnitude and direction at both points. C) The velocity components have the same magnitudes at both points, but their directions are reversed. D) The velocity components have the same magnitudes at both points, but the directions of the x components are reversed. E) The velocity components have the same magnitudes at both points, but the directions of the y components are reversed. Ans: E Refer To: Ref 3-6 Difficulty: Medium SectionDef: Section 3-2 and Section 3-3
42. Which statement is true concerning the ball when it is at C, the highest point in its trajectory? A) The ball's velocity and acceleration are both zero. B) The ball's velocity is perpendicular to its acceleration. C) The ball's velocity is not zero, but its acceleration is zero. D) The ball's velocity is zero, but its acceleration is not zero. E) The horizontal and vertical components of the ball's velocity are equal. Ans: B Refer To: Ref 3-6 Difficulty: Medium SectionDef: Section 3-2 and Section 3-3
43. At which point is the velocity vector changing most rapidly with time?
A) A B) B C) C D) D E) It is changing at the same rate at all four points. Ans: E Refer To: Ref 3-6 Difficulty: Hard SectionDef: Section 3-2 and Section 3-3
Reference: Ref 3-7 A football is kicked with a speed of 18 m/s at an angle of 65° to the horizontal.
44. What are the respective horizontal and vertical components of the initial velocity of the football? A) 7.6 m/s, 16 m/s B) 16 m/s, 7.6 m/s C) 8.4 m/s, 13 m/s D) 13 m/s, 8.4 m/s E) 9 m/s, 9 m/s Ans: A Refer To: Ref 3-7 Difficulty: Easy SectionDef: Section 3-2 and Section 3-3
45. How long is the football in the air? Neglect air resistance. A) 1.1 s B) 1.6 s C) 2.0 s D) 3.3 s E) 4.0 s Ans: D Refer To: Ref 3-7
Difficulty: Medium SectionDef: Section 3-2 and Section 3-3
46. How far does the football travel horizontally before it hits the ground? A) 18 m B) 25 m C) 36 m D) 48 m E) 72 m Ans: B Refer To: Ref 3-7 Difficulty: Medium SectionDef: Section 3-2 and Section 3-3
Reference: Ref 3-8 A rock is kicked horizontally at a speed of 16 m/s from the edge of a cliff. The rock strikes the ground 65 m from the foot of the cliff of height H as suggested in the figure, which is not drawn to scale. Neglect air resistance.
47. How long is the rock in the air? A) 1.0 s B) 1.2 s C) 4.0 s D) 5.5 s E) 11.2 s Ans: C
Refer To: Ref 3-8 Difficulty: Easy SectionDef: Section 3-2 and Section 3-3
48. What is the approximate value of H, the height of the cliff? A) 27 m B) 54 m C) 78 m D) 150m E) 300 m Ans: C Refer To: Ref 3-8 Difficulty: Hard SectionDef: Section 3-2 and Section 3-3
Reference: Ref 3-9 A projectile is fired horizontally with an initial speed of 50.0 m/s. Neglect air resistance and assume the projectile does not strike the ground prior to the elapsed time mentioned in the associated problems. 49. What is the magnitude of the displacement of the projectile 3.00 s after it is fired? A) 29.4 m B) 44.1 m C) 150 m D) 156 m E) 194 m Ans: D Refer To: Ref 3-9 Difficulty: Medium SectionDef: Section 3-2 and Section 3-3
50. What is the speed of the projectile 3.00 s after it is fired? A) 29.4 m/s B) 50.0 m/s
C) 58.0 m/s D) 79.4 m/s E) 98.6 m/s Ans: C Refer To: Ref 3-9 Difficulty: Medium SectionDef: Section 3-2 and Section 3-3
51. What is the magnitude of the acceleration of the projectile 3.00 s after it is fired? A) 9.8 m/s2 B) 16.6 m/s2 C) 29.4 m/s2 D) 5.42 m/s2 E) zero m/s2 Ans: A Refer To: Ref 3-9 Difficulty: Easy SectionDef: Section 3-2 and Section 3-3
52. A motorcycle has a velocity of 24 m/s, due south as it passes a car with a velocity of 15 m/s, due north. What is the magnitude and direction of the velocity of the motorcycle as seen by the driver of the car? A) 9 m/s, north B) 9 m/s, south C) 15 m/s, north D) 39 m/s, north E) 39 m/s, south Ans: E Difficulty: Medium SectionDef: Section 3-4
53. A tennis ball is thrown vertically with an initial speed of 20.0 m/s at time t = 0 s. Approximately, what is the initial speed of the ball relative to an observer in a car that moves horizontally past the launch location with a constant speed of 30 m/s?
A) 10 m/s B) 20 m/s C) 30 m/s D) 36 m/s E) 50 m/s Ans: D Difficulty: Medium SectionDef: Section 3-4
Reference: Ref 3-10 During football practice, a football is kicked with a speed of 22 m/s at an angle of 60.0° relative to the positive x direction. At that instant, an observer rides past the football in a car that moves with a constant speed of 11 m/s in the positive x direction.
54. Determine the initial velocity of the ball relative to the observer in the car. A) 19 m/s in the +y direction B) 11 m/s in the +y direction C) 19 m/s at 60° to the +x direction D) 33 m/s at 60° to the +x direction E) 17 m/s at 60° to the +x direction Ans: A Refer To: Ref 3-10 Difficulty: Medium SectionDef: Section 3-4
55. Complete the following statement: According to the observer in the car, the ball will A) follow a parabolic path. B) follow a hyperbolic path. C) follow a path that is straight up and down in the y direction. D) follow a path that is straight across in the +x direction. E) follow a straight line that is angled (less than 90°) with respect to the x direction. Ans: C Refer To: Ref 3-10
Difficulty: Hard SectionDef: Section 3-4
Reference: Ref 3-11 Two cars approach each other on a straight and level road. Car A is traveling at 75 km/h, due north and car B is traveling at 45 km/h, due south. Both velocities are measured relative to the ground.
56. What is the velocity of car A relative to an observer in car B? A) 75 km/h, north B) 30 km/h, north C) 30 km/h, south D) 120 km/h, south E) 120 km/h, north Ans: E Refer To: Ref 3-11 Difficulty: Medium SectionDef: Section 3-4
57. At a certain instant, the distance between the cars is 15 km. How long will it take, in seconds, from that instant for the two cars to meet? A) 450 s B) 900 s C) 720 s D) 1200 s E) 1900 s Ans: A Refer To: Ref 3-11 Difficulty: Medium SectionDef: Section 3-4
58. A ferry can travel at an optimal speed of 8 km/h in still water measured relative to the shore. What is the optimal speed of the ferry, relative to the shore, if it moves perpendicular to a 6 km/h current? A) 4 km/h B) 8 km/h C) 10 km/h D) 14 km/h E) 28 km/h Ans: C Difficulty: Medium SectionDef: Section 3-4
59. A boat that can travel at 4.0 km/h in still water crosses a river with a current of 2.0 km/h. At what angle must the boat be pointed upstream (that is, relative to its actual path) to go straight across the river? A) 27° B) 30° C) 60° D) 63° E) 90° Ans: B Difficulty: Hard SectionDef: Section 3-4
Reference: Ref 3-12 A man at point A directs his rowboat due north toward point B, straight across a river of width 100 m. The river current is due east. The man starts across, rowing steadily at 0.75 m/s and reaches the other side of the river at point C, 150 m downstream from his starting point.
60. What is the speed of the river? A) 0.38 m/s B) 0.67 m/s C) 1.1 m/s D) 6.7 m/s E) 7.5 m/s Ans: C Refer To: Ref 3-12 Difficulty: Medium SectionDef: Section 3-4
61. While the man is crossing the river, what is his velocity relative to the shore? A) 1.35 m/s, 34° north of east B) 2.00 m/s, 56° north of east C) 1.74 m/s, 34° north of east D) 2.11 m/s, 34° north of east E) 2.50 m/s, 42° north of east Ans: A Refer To: Ref 3-12 Difficulty: Medium SectionDef: Section 3-4
62. Two cars A and B approach each other at an intersection. Car A is traveling south at 20 m/s, while car B is traveling east at 17 m/s. What is the velocity of car A as described by the
passengers in car B? A) 37 m/s, eastward B) 26 m/s, 40° south of east C) 26 m/s, 50° south of east D) 26 m/s, 50° south of west E) 26 m/s, 40° south of west Ans: D Difficulty: Medium SectionDef: Section 3-4
63. A passenger at rest on a flatbed train car fires a bullet straight up. The event is viewed by observers at rest on the station platform as the train moves past the platform with constant velocity. What is the trajectory of the bullet as described by the observers on the platform? A) a straight horizontal path in the direction of the train's velocity B) a straight vertical path up and down C) a circular path centered on the gun D) a straight diagonal path E) a parabolic path Ans: E Difficulty: Easy SectionDef: Section 3-4
64. Airplane One flies due east at 250 km/h relative to the ground. At the same time, Airplane Two flies 325 km/h, 35° north of east relative to the ground. What is the velocity of Airplane One relative to Airplane Two? A) 16 km/h, due west B) 270 km/h, due north C) 210 km/h, 55° south of east D) 170 km/h, 15° north of east E) 190 km/h, 85° south of west Ans: E Difficulty: Hard SectionDef: Section 3-4
65. On a two lane highway, a car is following a pickup truck. At one instant, the car has a speed of 32 m/s and is 184 m behind the truck. At the same time, the truck has a speed of 28 m/s. If neither vehicle accelerates, how long will it take the car to catch up to the truck? A) 4.8 s B) 24 s C) 46 s D) 82 s E) 96 s Ans: C Difficulty: Medium SectionDef: Section 3-4
66. A bicyclist is riding at a constant speed along a straight-line path. The rider throws a ball straight up to a height a few meters above her head. Ignoring air resistance, where will the ball land? A) behind the rider B) in front of the rider C) in the same hand that threw the ball D) in the opposite hand to the one that threw it E) This cannot be determined without knowing the speed of the rider and the maximum height of the ball. Ans: C Difficulty: Medium SectionDef: Additional Problems
67. A basketball player is running at a constant speed of 2.5 m/s when he tosses a basketball upward with a speed of 6.0 m/s. How far does the player run before he catches the ball? Ignore air resistance. A) 3.1 m B) 4.5 m C) The ball cannot be caught because it will fall behind the player. D) 6.0 m E) 7.5 m Ans: A Difficulty: Hard SectionDef: Additional Problems
68. A ball is fired at an angle of 45°, the angle that yields the maximum range in the absence of air resistance. What is the ratio of the ball's maximum height to its range? A) 1.0 B) 0.75 C) 0.67 D) 0.50 E) 0.25 Ans: E Difficulty: Hard SectionDef: Additional Problems
Import Settings: Base Settings: Brownstone Default Information Field: Difficulty Information Field: SectionDef Highest Answer Letter: E Multiple Keywords in Same Paragraph: No
Chapter: Chapter 4
Multiple Choice
1. With one exception, each of the following units can be used to express mass. What is the exception? A) newton B) slug C) gram D) N•s2/m E) kilogram
Ans: A Difficulty: Easy SectionDef: Section 4-1, 4-2 and 4-3
2. Complete the following statement: The term net force most accurately describes A) the mass of an object B) the inertia of an object. C) the quantity that causes a displacement. D) the quantity that keeps an object moving. E) the quantity that changes the velocity of an object. Ans: E Difficulty: Easy SectionDef: Section 4-1, 4-2 and 4-3
3. Which one of the following terms is used to indicate the natural tendency of an object to remain at rest or in motion at a constant speed along a straight line? A) velocity B) inertia C) acceleration D) equilibrium E) force Ans: B Difficulty: Easy SectionDef: Section 4-1, 4-2 and 4-3
4. Complete the following statement: An inertial reference frame is one in which A) Newton's first law of motion is valid. B) the inertias of objects within the frame are zero. C) the frame is accelerating. D) the acceleration due to gravity is greater than zero m/s2. E) Newton's second law of motion is not valid. Ans: A Difficulty: Medium
SectionDef: Section 4-1, 4-2 and 4-3
5. A net force F is required to give an object with mass m an acceleration a. If a net force 6 F is applied to an object with mass 2m, what is the acceleration on this object? A) a B) 2 a C) 3 a D) 4 a E) 6 a Ans: C Difficulty: Easy SectionDef: Section 4-1, 4-2 and 4-3
6. When the net force that acts on a hockey puck is 12 N, the puck accelerates at a rate of 48 m/s2. Determine the mass of the puck. A) 0.25 kg B) 1.0 kg C) 5.0 kg D) 2.5 kg E) 2.0 kg Ans: A Difficulty: Medium SectionDef: Section 4-1, 4-2 and 4-3
7. The figure shows the velocity versus time curve for a car traveling along a straight line. Which of the following statements is false?
A) No net force acts on the car during interval B. B) Net forces act on the car during intervals A and C. C) Opposing forces may be acting on the car during interval B. D) Opposing forces may be acting on the car during interval C. E) The magnitude of the net force acting during interval A is less than that during C. Ans: E Difficulty: Medium SectionDef: Section 4-1, 4-2 and 4-3
8. The graph shows the velocities of two objects of equal mass as a function of time. Net forces FA, FB, and FC acted on the objects during intervals A, B, and C, respectively. Which one of the following choices is the correct relationship between the magnitudes of the net forces?
A) FB = FC > FA B) FC > FB > FA C) FA > FB = FC D) FA = FB = FC E) FA > FB > FC Ans: C Difficulty: Medium SectionDef: Section 4-1, 4-2 and 4-3
9. A net force of 25 N is applied for 5.7 s to a 12-kg box initially at rest. What is the speed of the box at the end of the 5.7-s interval? A) 1.8 m/s B) 12 m/s C) 3.0 m/s D) 7.5 m/s E) 30 m/s Ans: B Difficulty: Hard SectionDef: Section 4-1, 4-2 and 4-3
10. A 975-kg car accelerates from rest to 26.7 m/s in a distance of 120 m. What is the magnitude of the average net force acting on the car? A) 740 N B) 2900 N C) 91 N D) 1300 N E) 7900 N Ans: B Difficulty: Medium SectionDef: Section 4-1, 4-2 and 4-3
11. A 2150-kg truck is traveling along a straight, level road at a constant speed of 55.0 km/h when the driver removes his foot from the accelerator. After 21.0 s, the truck's speed is 33.0 km/h. What is the magnitude of the average net force acting on the truck during the 21.0 s interval? A) 2250 N B) 626 N C) 1890 N D) 972 N E) 229 N Ans: B Difficulty: Hard SectionDef: Section 4-1, 4-2 and 4-3
Reference: Ref 4-1 A 2.0-kg object moves in a straight line on a horizontal frictionless surface. The graph shows the velocity of the object as a function of time. The various equal time intervals are labeled using Roman numerals: I, II, III, IV, and V.
The net force on the object always acts along the line of motion of the object.
12. Which section(s) of the graph corresponds to a condition of zero net force? A) V only B) III only C) II and IV D) II, III, and IV E) I, III, and V Ans: C Refer To: Ref 4-1 Difficulty: Medium SectionDef: Section 4-1, 4-2 and 4-3
13. Which section of the graph corresponds to the application of the largest constant net force? A) I B) II C) III D) IV E) V
Ans: C Refer To: Ref 4-1 Difficulty: Medium SectionDef: Section 4-1, 4-2 and 4-3
14. In which section of the graph is the magnitude of the net force decreasing? A) I B) II C) III D) IV E) V Ans: A Refer To: Ref 4-1 Difficulty: Hard SectionDef: Section 4-1, 4-2 and 4-3
15. In which section(s) of the graph is the net force changing? A) I and III B) II and IV C) III D) IV E) I and V Ans: E Refer To: Ref 4-1 Difficulty: Hard SectionDef: Section 4-1, 4-2 and 4-3
16. An object moves due east at constant speed. A net force directed due north then acts on the object for 5.0 s. At the end of the 5.0-second period, the net force drops to zero newtons. Which one of the following statements is necessarily true? A) The object will be moving eastward when the force drops to zero newtons. B) The change in the velocity of the object is directed north of west. C) The direction of the object's acceleration depends on how fast the object was initially moving.
D) The final velocity of the object is directed north of east. E) The magnitude of the object's acceleration depends on how fast the object was initially moving. Ans: D Difficulty: Medium SectionDef: Section 4-4 and 4-5
17. Two forces act on a 16-kg object. The first force has a magnitude of 68 N and is directed 24° north of east. The second force is 32 N, 48° north of west. What is the acceleration of the object resulting from the application of these two forces to the object? A) 1.6 m/s2, 5.5° north of east B) 1.9 m/s2, 18° north of west C) 2.4 m/s2, 34° north of east D) 3.6 m/s2, 5.5° north of west E) 4.1 m/s2, 52° north of east Ans: E Difficulty: Hard SectionDef: Section 4-4 and 4-5
18. An apple crate with a weight of 225 N accelerates along a frictionless surface as the crate is pulled with a force of 14.5 N as shown in the drawing. What is the horizontal acceleration of the crate?
A) 1.40 m/s2 B) 0.427 m/s2 C) 1.29 m/s2 D) 0.597 m/s2 E) 0.644 m/s2 Ans: D Difficulty: Medium SectionDef: Section 4-4 and 4-5
19. Two forces act on a 4.5-kg block resting on a frictionless surface as shown. What is the magnitude of the horizontal acceleration of the block?
A) 1.8 m/s2 B) 1.2 m/s2 C) 0.82 m/s2 D) 3.2 m/s2 E) 8.9 m/s2 Ans: A Difficulty: Medium SectionDef: Section 4-4 and 4-5
20. Two forces act on a hockey puck. For which orientation of the forces will the puck acquire an acceleration with the largest magnitude?
A)
B) C)
D) E) The magnitude of the acceleration will be the same in all four cases shown above. Ans: C Difficulty: Easy SectionDef: Section 4-4 and 4-5
Reference: Ref 4-2 A horse pulls a cart along a flat road. Consider the following four forces that arise in this situation. (1) the force of the horse pulling on the cart (3) the force of the horse pushing on the road (2) the force of the cart pulling on the horse (4) the force of the road pushing on the horse
21. Which two forces form an "action-reaction" pair that obeys Newton's third law? A) 1 and 4 B) 1 and 3 C) 2 and 4 D) 3 and 4 E) 2 and 3 Ans: D Refer To: Ref 4-2 Difficulty: Easy SectionDef: Section 4-4 and 4-5
22. Suppose that the horse and cart have started from rest; and as time goes on, their speed increases in the same direction. Which one of the following conclusions is correct concerning the magnitudes of the forces mentioned above? A) Force 1 exceeds force 2. B) Force 2 is less than force 3. C) Force 2 exceeds force 4. D) Force 3 exceeds force 4. E) Forces 1 and 2 cannot have equal magnitudes. Ans: B Refer To: Ref 4-2 Difficulty: Medium SectionDef: Section 4-4 and 4-5
Reference: Ref 4-3 A physics student in a hot air balloon ascends vertically at constant speed. Consider the following four forces present in this situation:
F 1 = the weight of the hot air balloon F 2 = the weight of the student
F 3 = the force of the student pulling on the earth
F 4 = the force of the hot air balloon pulling on the student
23. Which two forces form an "action-reaction" pair that obeys Newton's third law? A) F 1 and F 2 B) F 2 and F 3 C) F 1 and F 3 D) F 2 and F 4 E) F 3 and F 4 Ans: B Refer To: Ref 4-3 Difficulty: Easy SectionDef: Section 4-4, 4-5, and 4-6
24. Which one of the following relationships concerning the forces or their magnitudes is true? A) F4 > F2 B) F1 < F2 C) F4 > F1 D) F 2 = – F 4 E) F 3 = – F 4 Ans: D Refer To: Ref 4-3 Difficulty: Medium SectionDef: Section 4-4 and 4-5
Reference: Ref 4-4 A book is resting on the surface of a table. Consider the following four forces that arise in this situation: (1) the force of the earth pulling on the book (3) the force of the book pushing on the table (2) the force of the table pushing on the book (4) the force of the book pulling on the earth
25. Which two forces form an "action-reaction" pair that obeys Newton's third law? A) 1 and 2 B) 1 and 3 C) 1 and 4 D) 2 and 4 E) 3 and 4 Ans: C Refer To: Ref 4-4 Difficulty: Easy SectionDef: Section 4-4, 4-5, 4-6, 4-7, and 4-8
26. The book has an acceleration of 0 m/s2. Which pair of forces, excluding "action-reaction" pairs, must be equal in magnitude and opposite in direction? A) 1 and 2 B) 1 and 3 C) 1 and 4 D) 2 and 3 E) 2 and 4 Ans: A Refer To: Ref 4-4 Difficulty: Medium SectionDef: Section 4-4, 4-5, 4-6, 4-7, and 4-8
Reference: Ref 4-5 A 70.0-kg astronaut pushes to the left on a spacecraft with a force F in “gravity-free” space. The spacecraft has a total mass of 1.0 × 104 kg. During the push, the astronaut accelerates to the right with an acceleration of 0.36 m/s2.
27. Which one of the following statements concerning this situation is true? A) The spacecraft does not move, but the astronaut moves to the right with a constant speed. B) The astronaut stops moving after he stops pushing on the spacecraft. C) The force exerted on the astronaut is larger than the force exerted on the spacecraft. D) The force exerted on the spacecraft is larger than the force exerted on the astronaut. E) The velocity of the astronaut increases while he is pushing on the spacecraft. Ans: E Refer To: Ref 4-5 Difficulty: Easy SectionDef: Section 4-4 and 4-5
28. Determine the magnitude of the acceleration of the spacecraft. A) 51.4 m/s2 B) 0.36 m/s2 C) 2.5 × 10–3 m/s2 D) 7.0 × 10–3 m/s2 E) 3.97 × 10–4 m/s2 Ans: C Refer To: Ref 4-5 Difficulty: Medium SectionDef: Section 4-4 and 4-5
29. Consider the following forces. (1) frictional (2) gravitational (3) tension electroweak
(4) strong nuclear
(5) normal
(6)
Which of the forces listed are considered fundamental forces? A) 1, 2, and 4 B) 1, 2, 3, and 5 C) 1, 3, and 5 D) 2, 4, and 6 E) 2, 3, 4, and 6 Ans: D Difficulty: Medium SectionDef: Section 4-6 and 4-7
30. A rock is thrown straight up from the earth's surface. Which one of the following statements concerning the net force acting on the rock at the top of its path is true? A) The net force is equal to the weight of the rock. B) The net force is instantaneously equal to zero newtons. C) The direction of the net force changes from up to down. D) The net force is greater than the weight of the rock. E) The net force is less than the weight of the rock, but greater than zero newtons. Ans: A Difficulty: Medium SectionDef: Section 4-6 and 4-7
31. Two point masses m and M are separated by a distance d. If the distance between the masses is increased to 3d, how does the gravitational force between them change? A) The force will be one-third as great. B) The force will be one-ninth as great. C) The force will be three times as great. D) The force will be nine times as great. E) It is impossible to determine without knowing the numerical values of m, M, and d. Ans: B Difficulty: Easy SectionDef: Section 4-6 and 4-7
32. Two point masses m and M are separated by a distance d. If the separation d remains fixed and the masses are increased to the values 3m and 3M respectively, how does the gravitational
force between them change? A) The force will be one-third as great. B) The force will be one-ninth as great. C) The force will be three times as great. D) The force will be nine times as great. E) It is impossible to determine without knowing the numerical values of m, M, and d. Ans: D Difficulty: Medium SectionDef: Section 4-6 and 4-7
33. Which one of the following statements concerning the two "gravitational constants" G, the universal gravitational constant, and g the magnitude of the acceleration due to gravity is true? A) The values of g and G depend on location. B) The values of g and G do not depend on location. C) The value of G is the same everywhere in the universe, but the value of g is not. D) The value of g is the same everywhere in the universe, but the value of G is not. E) The values of g and G are equal on the surface of any planet, but in general, G varies with location in the universe. Ans: C Difficulty: Easy SectionDef: Section 4-6 and 4-7
34. Two satellites of different masses are in the same circular orbit around the earth. Which one of the following statements is true concerning the magnitude of the gravitational force that acts on each of them? A) The magnitude of the gravitational force is zero newtons for both satellites. B) The magnitude of the gravitational force is the same for both satellites, but not zero newtons. C) The magnitude of the gravitational force is zero newtons for one, but not for the other. D) The magnitude of the gravitational force depends on their masses. E) The magnitude of the gravitational force varies from point to point in their orbits. Ans: D Difficulty: Medium SectionDef: Section 4-6 and 4-7
35. An astronaut orbits the earth in a space capsule whose height above the earth is equal to the earth's radius. How does the weight of the astronaut in the capsule compare to her weight on the earth? A) Her weight is equal to zero newtons. B) Her weight is approximately equal to one-fourth her weight on earth. C) Her weight is approximately equal to one-half of her weight on earth. D) Her weight is approximately equal to one-third of her weight on earth. E) Her weight is approximately equal to one-sixteenth her weight on earth. Ans: B Difficulty: Medium SectionDef: Section 4-6 and 4-7
36. An astronaut orbits the earth in a space capsule whose height above the earth is equal to the earth's radius. How does the mass of the astronaut in the capsule compare to her mass on the earth? A) Her mass is equal to her mass on earth. B) Her mass is approximately equal to one-fourth her mass on earth. C) Her mass is approximately equal to one-half of her mass on earth. D) Her mass is approximately equal to one-third of her mass on earth. E) Her mass is approximately equal to one-sixteenth her mass on earth. Ans: A Difficulty: Medium SectionDef: Section 4-6 and 4-7
37. Which one of the following statements best explains why the weight of an object of mass m is different on Mars than it is on the Earth? A) The mass of Mars is different from that of Earth. B) The masses and radii of Mars and Earth are not the same. C) The mass m is further from the Earth's center when it is on Mars. D) The constant G is different on Mars. E) The mass m will be different on Mars. Ans: B Difficulty: Easy SectionDef: Section 4-6 and 4-7
38. What is the weight of a 2.50-kg bag of sand on the surface of the earth? A) 2.50 N B) 9.80 N C) 24.5 N D) 49.0 N E) 98.0 N Ans: C Difficulty: Easy SectionDef: Section 4-6 and 4-7
39. A 2.00-kg projectile is fired at an angle of 20.0°. What is the magnitude of the force exerted on the projectile when it is at the highest position in its trajectory? Neglect any effects of air resistance. A) 19.6 N B) 14.7 N C) 9.80 N D) 4.90 N E) 0 N Ans: A Difficulty: Hard SectionDef: Section 4-6 and 4-7
40. A marble is dropped straight down from a distance h above the floor. Let Fm = the magnitude of the gravitational force on the marble due to the earth; Fe = the magnitude of the gravitational force on the earth due to the marble; am = the magnitude of the acceleration of the marble toward the earth; ae = the magnitude of the acceleration of the earth toward the marble. Which set of conditions is true as the marble falls toward the earth? Neglect any effects of air resistance. A) Fm = Fe and am < ae B) Fm < Fe and am > ae C) Fm < Fe and am = ae D) Fm > Fe and am = ae E) Fm = Fe and am > ae Ans: E Difficulty: Medium
SectionDef: Section 4-6 and 4-7
41. What is the magnitude of the gravitational force acting on a 79.5-kg student due to a 58.0-kg student sitting 2.40 m away in the classroom? A) 3.14 × 10–9 N B) 5.33 × 10–8 N C) 7.91 × 10–10 N D) 1.41 × 10–7 N E) 6.29 × 10–8 N Ans: B Difficulty: Medium SectionDef: Section 4-6 and 4-7
42. A 44-kg child steps onto a scale and the scale reads 430 N. What is the magnitude of the normal force acting on the child? A) 44 N B) 215 N C) 430 N D) 645 N E) 860 N Ans: C Difficulty: Easy SectionDef: Section 4-7 and 4-8
Reference: Ref 4-6 A force P pulls on a crate of mass m that is in contact with a rough surface. The figure shows the magnitudes and directions of the forces that act on the crate in this situation. W represents the weight of the crate. frictional force.
FN represents the normal force on the crate, and f represents the
43. Which statement best describes the motion of the crate? A) The crate must be at rest. B) The crate must be moving with constant velocity. C) The crate must be moving with constant acceleration. D) The crate may be either at rest or moving with constant velocity. E) The crate may be either at rest or moving with constant acceleration. Ans: D Refer To: Ref 4-6 Difficulty: Medium SectionDef: Section 4-4, 4-8 and 4-9
44. What is the magnitude of FN , the normal force on the crate? A) 57 N B) 80 N C) 160 N D) 196 N E) 230 N Ans: A Refer To: Ref 4-6 Difficulty: Medium SectionDef: Section 4-8 and 4-9
45. A 8-kg block is set moving with an initial speed of 6 m/s on a rough horizontal surface. If
the force of friction is 12 N, approximately how far does the block travel before it stops? A) 1.5 m B) 3 m C) 6 m D) 9 m E) 12 m Ans: E Difficulty: Hard SectionDef: Section 4-3, 4-4, 4-8 and 4-9
46. The wheels of an automobile are locked as it slides to a stop from an initial speed of 30.0 m/s. If the coefficient of kinetic friction is 0.600 and the road is horizontal, approximately how long does it take the car to stop? A) 4.22 s B) 5.10 s C) 8.75 s D) 10.4 s E) 15.3 s Ans: B Difficulty: Hard SectionDef: Section 4-3, 4-4, 4-8 and 4-9
47. A 250-N force is directed horizontally as shown to push a 29-kg box up an inclined plane at a constant speed. Determine the magnitude of the normal force, FN, and the coefficient of kinetic friction, µk.
FN
µk
A) 330 N B) 310 N C) 250 N D) 290 N E) 370 N
0.31 0.33 0.27 0.30 0.26
Ans: E
Difficulty: Hard SectionDef: Section 4-8 and 4-9
Reference: Ref 4-7 Two blocks rest on a horizontal frictionless surface as shown. The surface between the top and bottom blocks is roughened so that there is no slipping between the two blocks. A 30-N force is applied to the bottom block as suggested in the figure.
48. What is the acceleration of the "two block" system? A) 1 m/s2 B) 2 m/s2 C) 3 m/s2 D) 6 m/s2 E) 15 m/s2 Ans: B Refer To: Ref 4-7 Difficulty: Easy SectionDef: Section 4-3, 4-4, 4-8, and 4-9
49. What is the force of static friction between the top and bottom blocks? A) zero newtons B) 10 N C) 20 N D) 25 N E) 30 N Ans: B Refer To: Ref 4-7 Difficulty: Hard SectionDef: Section 4-3, 4-4 4-8 and 4-9
50. What is the minimum coefficient of static friction necessary to keep the top block from slipping on the bottom block? A) 0.05 B) 0.10 C) 0.20 D) 0.30 E) 0.40 Ans: C Refer To: Ref 4-7 Difficulty: Medium SectionDef: Section 4-3, 4-4 4-8 and 4-9
51. Note the following situations:
In which case will the magnitude of the normal force on the block be equal to (Mg + F sin )? A) case 1 only B) case 2 only C) both cases 1 and 2 D) both cases 2 and 3 E) cases 1, 2, and 3 Ans: A Difficulty: Medium SectionDef: Section 4-8 and 4-9
Reference: Ref 4-8 A block is pulled along a rough level surface at constant speed by the force P . The figure shows
the free-body diagram for the block. FN represents the normal force on the block; and f represents the force of kinetic friction.
52. What is the magnitude of FN ? A) 2mg B) P C) f D) mg E) This cannot be determined from the information given. Ans: D Refer To: Ref 4-8 Difficulty: Easy SectionDef: Section 4-8 and 4-9
53. If the coefficient of kinetic friction, k , between the block and the surface is 0.30 and the magnitude of the frictional force is 80.0 N, what is the weight of the block? A) 1.6 N B) 4.0 N C) 160 N D) 270 N E) 410 N Ans: D Refer To: Ref 4-8 Difficulty: Medium SectionDef: Section 4-8 and 4-9
54. Two identical blocks are pulled along a rough surface as suggested in the figure. Which one of the following statements is false?
A) The coefficient of kinetic friction is the same in each case. B) A force of the same magnitude is needed to keep each block moving. C) A force of the same magnitude was required to start each block moving. D) The normal force exerted on the blocks by the surface is the same for both blocks. E) The magnitude of the force of kinetic friction is greater for the block on the right. Ans: E Difficulty: Medium SectionDef: Section 4-8 and 4-9
55. A crate rests on the flatbed of a truck that is initially traveling at 15 m/s on a level road. The driver applies the brakes and the truck is brought to a halt in a distance of 38 m. If the deceleration of the truck is constant, what is the minimum coefficient of friction between the crate and the truck that is required to keep the crate from sliding? A) 0.20 B) 0.30 C) 0.39 D) 0.59 E) This cannot be determined without knowing the mass of the crate. Ans: B Difficulty: Hard SectionDef: Section 4-3, 4-4, 4-8 and 4-9
Reference: Ref 4-9 A 2.0-N force acts horizontally on a 10-N block that is initially at rest on a horizontal surface. The coefficient of static friction between the block and the surface is 0.50.
56. What is the magnitude of the frictional force that acts on the block? A) 0 N B) 2 N C) 5 N D) 8 N E) 10 N Ans: B Refer To: Ref 4-9 Difficulty: Medium SectionDef: Section 4-8 and 4-9
57. Suppose that the block now moves across the surface with constant speed under the action of a horizontal 3.0-N force. Which one of the following statements concerning this situation is false? A) The block is not accelerated. B) The net force on the block is zero newtons. C) The frictional force on the block has magnitude 3.0 N. D) The coefficient of kinetic friction between the block and the surface is 0.30. E) The direction of the total force that the surface exerts on the block is vertically upward. Ans: E Refer To: Ref 4-9 Difficulty: Easy SectionDef: Section 4-8 and 4-9
58. A 2.0-N rock slides on a frictionless inclined plane. Which one of the following statements is true concerning the normal force that the plane exerts on the rock?
A) The normal force is zero newtons. B) The normal force is 2.0 N. C) The normal force is less than 2.0 N, but greater than zero newtons. D) The normal force is greater than 2.0 N. E) It increases as the angle of inclination, , is increased.
Ans: C Difficulty: Medium SectionDef: Section 4-8 and 4-9
59. A boy pulls a 5.0-kg sled with a rope that makes a 60.0° angle with respect to the horizontal surface of a frozen pond. The boy pulls on the rope with a force of 10.0 N; and the sled moves with constant velocity. What is the coefficient of friction between the sled and the ice? A) 0.09 B) 0.12 C) 0.18 D) 0.06 E) 0.24 Ans: B Difficulty: Medium SectionDef: Section 4-8 and 4-9
60. In an experiment with a block of wood on an inclined plane, with dimensions shown in the figure, the following observations are made:
(1) If the block is placed on the inclined plane, it remains there at rest. (2) If the block is given a small push, it will accelerate toward the bottom of the incline without any further pushing. Which one of the following statements is the best conclusion that can be drawn from these observations? A) The coefficient of kinetic friction must be negative. B) Both coefficients of friction must be less than 0.25. C) Both coefficients of friction must be greater than 0.25. D) The coefficient of static friction must be less than the coefficient of kinetic friction. E) The coefficient of static friction is greater than 0.25 while the coefficient of kinetic friction is less than 0.25. Ans: E Difficulty: Medium SectionDef: Section 4-8 and 4-9
61. A rock is suspended from a string and moves downward at constant speed. Which statement is true concerning the tension in the string if air resistance is ignored? A) The tension is zero newtons. B) The tension points downward. C) The tension is equal to the weight of the rock. D) The tension is less than the weight of the rock. E) The tension is greater than the weight of the rock. Ans: C Difficulty: Easy SectionDef: Section 4-10 and 4-11
62. A rock is suspended from a string; and it moves downward at constant speed. Which one of the following statements is true concerning the tension in the string if air resistance is not ignored? A) The tension is zero newtons. B) The tension points downward. C) The tension is equal to the weight of the rock. D) The tension is less than the weight of the rock. E) The tension is greater than the weight of the rock. Ans: D Difficulty: Medium SectionDef: Section 4-10 and 4-11
63. A rock is suspended from a string; and it accelerates downward. Which one of the following statements concerning the tension in the string is true? A) The tension points downward. B) The tension is less than the weight of the rock. C) The tension is equal to the weight of the rock. D) The tension is greater than the weight of the rock. E) The tension is independent of the magnitude of the rock's acceleration. Ans: B Difficulty: Medium SectionDef: Section 4-10 and 4-11
64. A rock is suspended from a string; and it accelerates upward. Which statement is true concerning the tension in the string? A) The tension points downward. B) The tension is less than the weight of the rock. C) The tension is equal to the weight of the rock. D) The tension is greater than the weight of the rock. E) The tension is independent of the magnitude of the rock's acceleration. Ans: D Difficulty: Medium SectionDef: Section 4-10 and 4-11
65. In a tug-of-war, each man on a 5-man team pulls with an average force of 500 N. What is the tension in the center of the rope? A) zero newtons B) 100 N C) 500 N D) 2500 N E) 5000 N Ans: E Difficulty: Medium SectionDef: Section 4-10 and 4-11
66. Under what condition(s) will an object be in equilibrium? A) If the object is either at rest or moving with constant velocity, it is in equilibrium. B) If the object is either moving with constant velocity or with constant acceleration, it is in equilibrium. C) Only if the object is at rest can it be in equilibrium. D) Only if the object is moving with constant velocity can it be in equilibrium. E) Only if the object is moving with constant acceleration can it be in equilibrium. Ans: A Difficulty: Medium SectionDef: Section 4-10 and 4-11
22. An elevator supported by a single cable descends a shaft at a constant speed. The only forces acting on the elevator are the tension in the cable and the gravitational force. Which one of the following statements is true? A) The magnitude of the work done by the tension force is larger than that done by the gravitational force. B) The magnitude of the work done by the gravitational force is larger than that done by the tension force. C) The work done by the tension force is zero joules. D) The work done by the gravitational force is zero joules. E) The net work done by the two forces is zero joules. Ans: E Difficulty: Medium SectionDef: Section 6-3 and 6-4
23. During the construction of a high rise building, 40-kg block is vertically lifted 20 meters from the surface of the earth. To one significant figure, what is the change in the gravitational potential energy of the block? A) +800 J B) –800 J C) +8000 J D) –8000 J E) zero joules Ans: C Difficulty: Easy SectionDef: Section 6-3 and 6-4
24. A 1500-kg elevator moves upward with constant speed through a vertical distance of 25 m. How much work was done by the tension in the elevator cable? A) 990 J B) 8100 J C) 140 000 J D) 370 000 J E) 430 000 J Ans: D Difficulty: Medium SectionDef: Section 6-3 and 6-4
25. Larry's gravitational potential energy is 1870 J as he sits 2.20 m above the ground in a sky diving airplane before it takes off. What is Larry's gravitational potential energy when he begins to jump from the airplane at an altitude of 923 m? A) 7.85 × 105 J B) 1.87 × 103 J C) 3.29 × 104 J D) 9.36 × 102 J E) 4.22 × 106 J Ans: A Difficulty: Medium SectionDef: Section 6-3 and 6-4
26. Two balls of equal size are dropped from the same height from the roof of a building. One ball has twice the mass of the other. When the balls reach the ground, how do the kinetic energies of the two balls compare? A) The lighter one has one fourth as much kinetic energy as the other does. B) The lighter one has one half as much kinetic energy as the other does. C) The lighter one has the same kinetic energy as the other does. D) The lighter one has twice as much kinetic energy as the other does. E) The lighter one has four times as much kinetic energy as the other does. Ans: B Difficulty: Medium SectionDef: Section 6-3 and 6-4
27. A 12-kg crate is pushed up an incline from point A to point B as shown in the figure. What is the change in the gravitational potential energy of the crate?
A) +590 J B) –590 J C) +1200 J
D) –1200 J E) This cannot be determined without knowing the angle of the incline. Ans: A Difficulty: Medium SectionDef: Section 6-3 and 6-4
28. A woman stands on the edge of a cliff and throws a stone vertically downward with an initial speed of 10 m/s. The instant before the stone hits the ground below, it has 450 J of kinetic energy. If she were to throw the stone horizontally outward from the cliff with the same initial speed of 10 m/s, how much kinetic energy would it have just before it hits the ground? A) 50 J B) 100 J C) 450 J D) 800 J E) 950 J Ans: C Difficulty: Medium SectionDef: Section 6-3 and 6-4
29. A donkey pulls a crate up a rough, inclined plane at constant speed. Which one of the following statements concerning this situation is false? A) The gravitational potential energy of the crate is increasing. B) The net work done by all the forces acting on the crate is zero joules. C) The work done on the crate by the normal force of the plane is zero joules. D) The donkey does "positive" work in pulling the crate up the incline. E) The work done on the object by gravity is zero joules. Ans: E Difficulty: Medium SectionDef: Section 6-3 and 6-4
30. A block is dropped from a high tower and is falling freely under the influence of gravity. Which one of the following statements is true concerning this situation? Neglect air resistance. A) As the block falls, the net work done by all of the forces acting on the block is zero joules. B) The kinetic energy increases by equal amounts over equal distances.
C) The kinetic energy of the block increases by equal amounts in equal times. D) The potential energy of the block decreases by equal amounts in equal times. E) The total energy of the block increases by equal amounts over equal distances. Ans: B Difficulty: Hard SectionDef: Section 6-3 and 6-4
31. A rock is thrown straight up from the surface of the Earth. Which one of the following statements describes the energy transformation of the rock as it rises? Neglect air resistance. A) The total energy of the rock increases. B) The kinetic energy increases and the potential energy decreases. C) Both the potential energy and the total energy of the rock increase. D) The kinetic energy decreases and the potential energy increases. E) Both the kinetic energy and the potential energy of the rock remain the same. Ans: D Difficulty: Medium SectionDef: Section 6-3 and 6-4
32. Complete the following statement: A force that acts on an object is said to be conservative if A) it obeys Newton's laws of motion. B) it results in a change in the object's kinetic energy. C) it always acts in the direction of motion of the object. D) the work it does on the object is independent of the path of the motion. E) the work it does on the object is equal to the increase in the object's kinetic energy. Ans: D Difficulty: Medium SectionDef: Section 6-3 and 6-4
33. Which one of the following choices is an example of a conservative force? A) tension B) normal force C) static frictional force D) motor propulsion force E) elastic spring force
Ans: E Difficulty: Easy SectionDef: Section 6-3 and 6-4
34. Which one of the following choices is an example of a non-conservative force? A) gravitational force B) electrical force C) kinetic frictional force D) elastic spring force Ans: C Difficulty: Easy SectionDef: Section 6-3 and 6-4
35. A helicopter (m = 3250 kg) is cruising at a speed of 56.9 m/s at an altitude of 185 m. What is the total mechanical energy of the helicopter? A) 3.91 × 107 J B) 5.26 × 106 J C) 2.27 × 108 J D) 6.91 × 107 J E) 1.12 × 108 J Ans: E Difficulty: Easy SectionDef: Section 6-5
36. A pebble rolls off the roof of Science Hall and falls vertically. Just before it reaches the ground, the pebble's speed is 17 m/s. Neglect air resistance and determine the height of Science Hall. A) 42 m B) 33 m C) 26 m D) 21 m E) 15 m Ans: E
Difficulty: Medium SectionDef: Section 6-5
Reference: Ref 6-1 A 2.0-kg projectile is fired with initial velocity components vox = 30 m/s and voy = 40 m/s from a point on the earth's surface. Neglect any effects due to air resistance.
37. What is the kinetic energy of the projectile when it reaches the highest point in its trajectory? A) zero joules B) 900 J C) 1600 J D) 2500 J E) 4900 J Ans: B Refer To: Ref 6-1 Difficulty: Medium SectionDef: Section 6-5
38. How much work was done in firing the projectile? A) 900 J B) 1600 J C) 2500 J D) 4900 J E) 9800 J Ans: C Refer To: Ref 6-1 Difficulty: Hard SectionDef: Section 6-5
39. Two boxes are connected to each other as shown. The system is released from rest and the 1.00-kg box falls through a distance of 1.00 m. The surface of the table is frictionless. What is
the kinetic energy of box B just before it reaches the floor?
A) 2.45 J B) 4.90 J C) 9.80 J D) 29.4 J E) 39.2 J Ans: A Difficulty: Hard SectionDef: Section 6-5
40. A roller-coaster car is moving at 20 m/s along a straight horizontal track. What will its speed be after climbing the 15-m hill shown in the figure, if friction is ignored?
A) 17 m/s B) 7 m/s C) 5 m/s D) 10 m/s E) 14 m/s Ans: D Difficulty: Medium SectionDef: Section 6-5
41. A 3.0-kg cylinder falls vertically from rest in a very tall, evacuated tube near the surface of the earth. What is its speed after the cylinder has fallen 6.0 m?
A) 8.0 m/s B) 11 m/s C) 13 m/s D) 120 m/s E) 26 m/s Ans: B Difficulty: Easy SectionDef: Section 6-5
42. A bicyclist is traveling at a speed of 20.0 m/s as he approaches the bottom of a hill. He decides to coast up the hill and stops upon reaching the top. Neglecting friction, determine the vertical height of the hill. A) 28.5 m B) 3.70 m C) 11.2 m D) 40.8 m E) 20.4 m Ans: E Difficulty: Medium SectionDef: Section 6-5
43. A skier leaves the top of a slope with an initial speed of 5.0 m/s. Her speed at the bottom of the slope is 13 m/s. What is the height of the slope? A) 1.1 m B) 4.6 m C) 6.4 m D) 7.3 m E) 11 m Ans: D Difficulty: Medium SectionDef: Section 6-5
44. A roller coaster starts from rest at the top of an 18-m hill as shown. The car travels to the bottom of the hill and continues up the next hill that is 10.0 m high.
How fast is the car moving at the top of the 10.0-m hill, if friction is ignored? A) 6.4 m/s B) 8.1 m/s C) 13 m/s D) 18 m/s E) 27 m/s Ans: C Difficulty: Medium SectionDef: Section 6-5
45. An engineer is asked to design a playground slide such that the speed a child reaches at the bottom does not exceed 6.0 m/s. Determine the maximum height that the slide can be. A) 1.8 m B) 2.9 m C) 3.2 m D) 4.5 m E) 7.4 m Ans: A Difficulty: Medium SectionDef: Section 6-5
46. A care package is dropped from rest from a helicopter hovering 25 m above the ground. What is the speed of the package just before it reaches the ground? Neglect air resistance. A) 22 m/s B) 16 m/s C) 12 m/s D) 8.0 m/s E) 5.0 m/s Ans: A Difficulty: Easy
SectionDef: Section 6-5
Reference: Ref 6-2 A block of mass m is released from rest at a height R above a horizontal surface. The acceleration due to gravity is g. The block slides along the inside of a frictionless circular hoop of radius R.
47. Which one of the following expressions gives the speed of the mass at the bottom of the hoop? A) zero m/s2 B) v = mgR mg v 2R C) g2 v R D) 2 E) v = 2gR Ans: E 2
Refer To: Ref 6-2 Difficulty: Medium SectionDef: Section 6-5
48. What is the magnitude of the normal force exerted on the block by the hoop when the block reaches the bottom of the hoop? A) zero newtons B) mg2/R C) mg
D) 2mg E) 3mg Ans: E Refer To: Ref 6-2 Difficulty: Hard SectionDef: Section 6-5
49. A physics student shoves a 0.50-kg block from the bottom of a frictionless 30.0° inclined plane. The student performs 4.0 J of work and the block slides a distance s along the incline before it stops. Determine the value of s.
A) 8.0 cm B) 16 cm C) 82 cm D) 160 cm E) 330 cm Ans: D Difficulty: Hard SectionDef: Section 6-6
50. The initial velocity of a 4.0-kg box is 11 m/s, due west. After the box slides 4.0 m horizontally, its speed is 1.5 m/s. Determine the magnitude and the direction of the nonconservative force acting on the box as it slides. A) 42 N, due west B) 120 N, due east C) 31 N, due east D) 59 N, due east E) 83 N, due west Ans: D
Difficulty: Hard SectionDef: Section 6-6
51. An automobile approaches a barrier at a speed of 20 m/s along a level road. The driver locks the brakes at a distance of 50 m from the barrier. What minimum coefficient of kinetic friction is required to stop the automobile before it hits the barrier? A) 0.4 B) 0.5 C) 0.6 D) 0.7 E) 0.8 Ans: A Difficulty: Hard SectionDef: Section 6-6
Reference: Ref 6-3 A 9.0-kg box of oranges slides from rest down a frictionless incline from a height of 5.0 m. A constant frictional force, introduced at point A, brings the block to rest at point B, 19 m to the right of point A.
52. What is the speed of the box just before it reaches point A? A) 98 m/s B) 21 m/s C) 9.9 m/s D) 5.7 m/s E) 4.4 m/s
Ans: C Refer To: Ref 6-3 Difficulty: Medium SectionDef: Section 6-6
53. What is the coefficient of kinetic friction, k, of the surface from A to B? A) 0.11 B) 0.26 C) 0.33 D) 0.47 E) 0.52 Ans: B Refer To: Ref 6-3 Difficulty: Hard SectionDef: Section 6-6
54. The kinetic energy of a car is 8 × 106 J as it travels along a horizontal road. How much power is required to stop the car in 10 s? A) zero watts B) 8 × 104 W C) 8 × 105 W D) 8 × 106 W E) 8 × 107 W Ans: C Difficulty: Easy SectionDef: Section 6-7
55. A 51-kg woman runs up a flight of stairs in 5.0 s. Her net upward displacement is 5.0 m. Approximately, what average power did the woman exert while she was running? A) 5.0 kW B) 1.0 kW C) 0.75 kW D) 0.50 kW E) 0.25 kW
Ans: D Difficulty: Medium SectionDef: Section 6-7
56. What power is needed to lift a 49-kg person a vertical distance of 5.0 m in 20.0 s? A) 12.5 W B) 25 W C) 60 W D) 120 W E) 210 W Ans: D Difficulty: Medium SectionDef: Section 6-7
57. An escalator is 30.0 meters long and slants at 30.0° relative to the horizontal. If it moves at 1.00 m/s, at what rate does it do work in lifting a 50.0-kg woman from the bottom to the top of the escalator? A) 49.3 W B) 98.0 W C) 245 W D) 292 W E) 495 W Ans: C Difficulty: Hard SectionDef: Section 6-7
58. How much power is needed to lift a 75-kg student vertically upward at a constant speed of 0.33 m/s? A) 12.5 W B) 25 W C) 115 W D) 230 W E) 243 W
Ans: E Difficulty: Hard SectionDef: Section 6-7
59. A warehouse worker uses a forklift to raise a crate of pickles on a platform to a height 2.75 m above the floor. The combined mass of the platform and the crate is 207 kg. If the power expended by the forklift is 1440 W, how long does it take to lift the crate? A) 37.2 s B) 5.81 s C) 3.87 s D) 18.6 s E) 1.86 s Ans: C Difficulty: Hard SectionDef: Section 6-7
60. A dam is used to block the passage of a river and to generate electricity. Approximately 5.73 104 kg of water fall each second through a height of 19.6 m. If 85 % of the gravitational potential energy of the water were converted to electrical energy, how much power would be generated? A) 9.36 106 W B) 1.52 107 W C) 1.08 107 W D) 1.35 108 W E) 4.68 106 W Ans: A Difficulty: Hard SectionDef: Section 6-7
61. The amount of energy needed to power a 0.10-kW bulb for one minute would be just sufficient to lift a 1.0-kg object through a vertical distance of A) 12 m B) 75 m C) 100 m D) 120 m
E) 610 m Ans: E Difficulty: Medium SectionDef: Section 6-7
62. The graph shows the force component along the displacement as a function of the magnitude of the displacement. Determine the work done by the force during the interval from 2 to 10 m.
A) 140 J B) 180 J C) 270 J D) 450 J E) 560 J Ans: B
Difficulty: Medium SectionDef: Section 6-9
63. The force component acting on an object along the displacement varies with the displacement s as shown in the graph. Determine the work done on the object as it travels from s = 0.0 to 12 m.
A) 48 J B) 66 J C) 72 J D) 57 J E) 81 J Ans: B Difficulty: Medium SectionDef: Section 6-9
64. Which one of the following is not a unit of energy? A) foot pound B) kilowatt hour C) newton meter D) watt E) joule Ans: D Difficulty: Easy SectionDef: Additional Problems
Reference: Ref 6-4 A 0.50-kg ball on the end of a rope is moving in a vertical circle of radius 3.0 m near the surface of the Earth where the acceleration due to gravity, g, is 9.8 m/s2. Point A is at the top of the circle; C is at the bottom. Points B and D are exactly halfway between A and C.
65. Which one of the following statements concerning the tension in the rope is true? A) The tension is smallest at A. B) The tension is smallest at C. C) The tension is smallest at both B and D. D) The tension is the same at A and C. E) The tension is the same at A, B, C, and D. Ans: A Refer To: Ref 6-4 Difficulty: Easy SectionDef: Additional Problems
66. The ball moves on the circle from A to C under the influence of gravity alone. If the kinetic energy of the ball is 35 J at A, what is its kinetic energy at C? A) zero joules B) 29 J C) 35 J D) 44 J E) 64 J Ans: E Refer To: Ref 6-4 Difficulty: Medium SectionDef: Additional Problems