Newton’s 3 rd Law of Motion Action - Reaction Chapter 6.3

Newton’s 2 nd Law (a = F/m) Newton’s second law is responsible for explaining how objects increase or decrease in speed, or change direction. If the force is, the object will. If the mass is, the object will more. When an object, it is also said to be. Huh? You will see… Newton’s 2 nd Law can also be used to explain the forces that exist on stationary objects like your weight or the repulsive and attractive forces of two magnets.

What is the of a ? If you pull on a rope, do you feel the rope pull on you? Which is the source of the force, you or the rope?

All forces exist in (no ) that are in and equal in magnitude (size). When you kick a ball, you exert a force on the while the exerts a force on you. You pull on a to open it while the exerts a force on you. A exerts a force on a nail while the exerts a force on the hammer. When you on a rope, it on you.

Newton’s Law of Motion When one object exerts a force on another object, the second object exerts an equal but oppositely directed force on the first object. For there is an. (Newton’s ____ Law is sometimes referred to as the “ of -.”)

Free Body Diagram of Newton’s 3 rd Law of Motion = Note that the forces come in that have.

Action - Reaction Action Reaction ====== Note: All forces come in and pairs

What is the Force? You push on your desk. The on you. An airplane propeller pushes on the air. The on the airplane propeller. A tennis racquet hits a ball. A a tennis racquet. You push on the floor as you take a step. The back on you.

Do the forces cancel each other out?. Since the forces act on, it is possible for them to each other out. Force of person on floor. Force of floor on person. F f = m f a f F p = m p a p

Newton’s 3 rd Law of Motion & Acceleration Newton’s 3 rd Law of Motion says that ____ = ____ And Newton’s 2 nd Law of Motion says that ______ = ______ While the forces may be but opposite in direction, the of each object may be.

Example: Newton’s 3 rd Law of Motion A physics student is pulling on a rope, which in both cases causes the scale to read 500 Newtons. The physics student is pulling a. with more force when the rope is attached to the wall. b. with more force when the rope is attached to the elephant. c. the same force in each case.

Newton’s 3 rd Law of Motion? = Does the following diagram illustrate an action-reaction pair?, because both forces act on the object.

Key Ideas Newton’s 3 rd Law of Motion states that when two objects interact, the magnitude of the force exerted by object 1 on object 2 is to the of the force simultaneously exerted by object 2 on object 1, and are in directions. Newton’s 3 rd Law of Motion is also known as the of -. All forces in nature come in. While the forces are equal and opposite, they do each other out because the two forces act on objects.