Question

A ball falls from 20m height on floor and rebounds to 5m. Time of contact is 0.02 sec. Find accleration during impact

Answer 1

"so the ball deflects and decelerates to zero velocity on contact with the ground. The elastic potential energy which remains in the ball causes it to expand and accelerate.

Some energy is lost decelerating and accelerating the ball.

before release PE = mg(20)… after rebound PE = mg(5)

Energy lost = mg(20–5)= 15mg

Energy lost = Force x distance = s(m)a = 15mg

So average acceleration… a = 15mg/s = 15x9.81/0.02

"

Answer 2

Average Acceleration = 7350 m/s