IV. Interaction of forces and Momentum

1. forces occur in pairs (action and reaction) – force is an interaction between one object and another
2. Newton’s 3rd law: Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first – or to every action there is always an equal and opposite reaction
3. This seems absurd – but remember the same force has very different effect on different masses a = F/m
   2 objects can feel the same force but have very different results

1. basics
   1. momentum describes the how much of an effect a force will have on different objects – how much that object will resist the force
   2. depends on mass and velocity (directly proportional)
   3. momentum = mv (inertia in motions, resistence to change)
2. Change in Momentum
   1. Impulse = change in momentum = change in mv
   2. Impulse related to both force and the time over which it acts
   3. Ft = change in mv