A tennis ball is dropped on to the floor from a height of 10 m. It rebounds to a

height of 2.5 m. If the ball is in contact with the floor for 0.01 seconds, what is
the average acceleration during the contact?

1 answer

You have initial PE, so solve for velocity at floor. Then, you know PE at 2.5m, so you know initial rebound velocity.
acceleration= (Vrebound-Vinitial)/time remembering that Vrebound is exactly the opposite direction of Vinitialcontact....so they add.