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First Edition

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3.1 Types of Forces By: Gianna Monaco and Frank Monzo

Click on random images for fun facts and hints throughout the chapter!!


Unit 3.1 Introduction To Forces

Forces Key Concepts 1. Different types of forces 2. Learning The Formula 3. Free Body Diagrams 4. Finding The Net Force 5. Pogils 6. Lab

An object's velocity does not change on its own. As Newton's First Law states, "an object in motion stays in motion and an object at rest stays at rest unless acted upon by an opposing force.� Thus an interaction is required between the object to change the velocity. This interaction can be a direct force, known as a Contact force. An interaction may also take a place at a distance. Magnetic and gravitational forces are a few examples of at a distance force. Friction and normal forces are examples of contact forces. If there is an unbalanced net force, then the forces do not add up to zero. However, there is a common misconception that when all forces are applied to an object it will move. In fact, not all forces cause the object to move. For example, when a book is resting on a desk, there are still forces acting upon it even though it is at rest. There is a gravitational force acting upon the book and the normal force which is the desk keeping the book up. Those two forces cancel each other out, making the book stay still. In situations like this, the net force does add up to zero. When objects are in deep space, they experience a net force of zero, however still in constant velocity. This is caused because space is a vacuum, so the forces are exact opposite of each other. When objects have a net force of zero, they are in equilibrium. 2


unit 3.1

Lab/Activity

Directions: 1.) with the pen/pencil poke a hole near the rim of the cup, then do the same directly across the hole on the cup. 2.) cut two pieces of string to about 2 feet in length. Attach each string to one side of the cup by tying a knot.

Materials 1. String 2. A plastic cup 3. A  ball point pen or pencil 4. Penny

3.) take the strings and whip the cup with the penny or water inside it around in a circle.

Discussion Questions: Why did the penny and water did not fly out of the cup when it was flying through the air? What do you think helped the penny and water stay in the cup? What different forces do you think are acting in this situation?

5. Water A centrifugal force is an apparent force that acts outward on a body moving around a center, arising from the body's inertia. This keeps the object from flying out of the cup.

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Biblography Websites we used to help us create the book. http://www.skwirk.com/p-t_s-11_u-399_t-988/types-of-forces/nsw/sci ence-technology/forces-and-their-effects http://www.physicsclassroom.com/class/newtlaws/Lesson-2/Types-o f-Forces http://www.mwit.ac.th/~physicslab/applet_04/physics_classroom/Cla ss/newtlaws/u2l2b.html http://www.physicsclassroom.com/class/newtlaws/Lesson-2/Drawin g-Free-Body-Diagrams http://physics.wku.edu/phys201/Information/ProblemSolving/ForceD iagrams.html https://thenounproject.com/brandcut/collection/pens-pencils-sharpie s-markers/?q=cup

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Physics Final Project