posted by Sasha .
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?
(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