The Law of Conservation of Momentum

Example: A collision between two billiard balls.

• Detail: When one billiard ball strikes another, the total momentum before the collision equals the total momentum after the collision. If ball A (mass = 0.2 kg) moves at 2 m/s and collides with stationary ball B (mass = 0.2 kg), the momentum transfers, and after the collision, ball A may slow down while ball B gains speed.