1. Newton’s Third Law

2. Newton’s Third Law of Motion Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. “To every action there is an equal and opposite reaction” F(AB) = - F(BA) Forces come in pairs. In nature there is no single force (all by itself).

3. Examples I exert a force on a desk with my foot and the desk exerts a force back on my foot. (“I kick a desk and the desk kicks me back.”) A hammer exerts a force on a nail and the nail exerts a force back on the hammer.

4. Force “on” and “by” A force influences the motion of an object only when it is applied on that object. A force exerted by a body does not influence that body (itself); it only influences the OTHER body on which it is exerted. F(AB) = - F(BA)

5. Group Activity 1.Explain walking forward on East Bottom. 2.Explain birds flying south. 3.Explain a rocket lifting off Cape Canaveral. 4.A person throws a package out of a boat (initially at rest). 5.A bat exerts a 50 N force on a baseball. 6.An inflated, but untied, balloon flies off. 7.Earth exerts gravitation on the moon.