A tennis ball of mass 57.0 g is held just above a basketball of mass 647 g. With their centers vertically aligned, both balls are released from rest at the same time, to fall through a distance of 1.00 m, as shown in the figure below.

(a) Find the magnitude of the downward velocity with which the basketball reaches the ground. m/s
(b) Assume that an elastic collision with the ground instantaneously reverses the velocity of the basketball while the tennis ball is still moving down. Next, the two balls meet in an elastic collision. To what height does the tennis ball rebound?