You drop a ball from a height of 2.0 m and it bounces back to a height of 1.5 m (a) What fraction of its initial energy is lost during the bounce? (b) What is the ball’s speed just at it leaves the ground after the bounce?

Answer 1

(a) It equals the fraction of the potential energy that is lost, at max weight. That looks like 1/4 in this case.

(b) To achieve 3/4 of the previous max height, you need the bounceback speed to be sqrt(0.75) = 0.866 of the speed just before inpact