1. Conservation of Momentum

2. The total momentum of an isolated system of objects is constant
By system, we mean any set of objects which interact with each other. The system is isolated if there is no net external force.

3. If two billiard balls collide we consider the only significant force to be the brief, large forces they exert on each other. The two balls change momentum because of the collision, the total momentum remains the same.

4. momentum before = momentum after
mava + mbvb = mava’ + mbvb’ In this equation, we have two objects involved (a & b), but there can be any number of objects.

5. A 10 000kg railroad car travelling at 24
A kg railroad car travelling at 24.0m/s strikes an identical car at rest. If the cars lock together as a result of the collision, what is their speed afterward?
V=12.0m/s

6. Calculate the recoil velocity of a 5. 0kg rifle that shoots a 0
Calculate the recoil velocity of a 5.0kg rifle that shoots a 0.020kg bullet at a speed of 620m/s.
V= -2.5 m/s

7. A 26. 0kg child in a 45. 0 kg boat at rest throws a 6
A 26.0kg child in a 45.0 kg boat at rest throws a 6.40kg package horizontally out of the boat with a speed of 10.0m/s. What is the velocity of the boat immediately after.