Bobby throws a ball straight up in the air, and it reaches a maximum height of 20 meters, a pretty good throw! Which of the following is true about the velocity of the ball just before it hits the ground?
A)It is faster than the velocity with which the ball was thrown.
B)It is the same as the velocity with which the ball was thrown.
C)It is slower than the velocity with which the ball was thrown.
D)The velocity is 0.
E)The velocity is the same as when the ball reaches its maximum height.

Question

Quizplus · Accepted Answer

The ball will have the same velocity as when it was initially thrown. If the ball travels only 20 meters, air resistance is negligible. According to the potential energy equation, P = mgh, the energy at the peak height is the same as the kinetic energy when the ball was thrown. Thus the energy when the ball falls back down should be the same as well, resulting in a similar, if not same velocity.

Bobby Throws a Ball Straight Up in the Air, and It