Notes: Chapter 11.3 Newton’s Third Law of Motion and Momentum

Newton’s Third Law of Motion For every action force there is an equal and opposite reaction force. Called force pairs or action/reaction pairs Force pairs do not act on the same object, and thus don’t always have the same effect! Movie: Newton's third

Newton’s Third Law of Motion The equal forces don’t always have the same effect, though. According to the second law, F=ma. You will have different results depending on their masses.

Momentum An extension of Newton’s Third Law…tells what will happen from the action/reaction Is equal to mass x velocity p = mv units have no name, just kg. m/s

Momentum & Collisions In collisions, momentum is conserved, that is, it is the same for all the objects before and after the collision. It can be transferred … when one moving thing hits another, the other one can move, too.

Momentum & Collisions Elastic collision : objects hit each other and don’t stick together (bounce off) Inelastic collision : objects hit each other and stick together Momentum and Collisions Conservation of Momentum