A student bounces a tennis ball. She drops the ball, and then it bounces back up to her. When does the ball have zero kinetic energy?
Only one answer
Exactly when it hits the ground
As soon as she drops it
At the very top of its bounce
Just after it hits the ground
The correct answer is "At the very top of its bounce".
At the very top of its bounce, the ball momentarily comes to a stop before changing direction and falling back towards the ground. At this point, it has zero velocity and therefore zero kinetic energy.