How to Calculate the Speed of a Second Billiard Ball After Collision

What happens when a billiard ball moving at 2.2 m/s strikes a second billiard ball at rest?

A. The second billiard ball continues in the same direction
B. The second billiard ball moves in the opposite direction
C. The second billiard ball stops moving
D. The second billiard ball moves at a 45° angle

Answer:

The speed of the second billiard ball after the collision is 2.2 m/s.

When a billiard ball moving at 2.2 m/s strikes a second billiard ball at rest, the second billiard ball will move in the opposite direction from the first ball after the collision. Both billiard balls have the same mass, so the speed of the second billiard ball after the collision will be equal to the speed of the first ball, which is 2.2 m/s. This is due to the conservation of momentum principle, where the total momentum before the collision is equal to the total momentum after the collision.

Therefore, if the first billiard ball continues at a 45° angle from its original direction, the second billiard ball will move at a -45° angle from the same original direction, with a speed of 2.2 m/s. This demonstrates how the conservation of momentum can be used to calculate the speed of a billiard ball after a collision.