Question

A billiard ball collides with an identical stationary billiard ball. Assuming that the collision is elastic, which of the following is true of the ball that was originally stationary?

a) It moves in the opposite direction as the ball that collided with it, and it has half the velocity.
b) It moves in the same direction and with the same velocity as the ball that collided with it.
c) It remains stationary.

Answer 1

In an elastic collision between two identical billiard balls, the ball that was originally stationary will move in the same direction and with the same velocity as the ball that collided with it.

Step-by-step explanation:

In an elastic collision between two identical billiard balls, the ball that was originally stationary will move in the same direction and with the same velocity as the ball that collided with it.

This is because in an elastic collision, both momentum and kinetic energy are conserved. The momentum of the system is conserved because the total momentum before the collision is equal to the total momentum after the collision. In this case, since one ball is initially stationary, its momentum is zero. To conserve momentum, the other ball must move in the same direction with the same velocity as the initial moving ball.

Therefore, the correct answer is b) It moves in the same direction and with the same velocity as the ball that collided with it.