A boy throws directly downward an ideally elastic ball from theheight 4.80m. The ball is being bounced from the floor reaching certain (unknown) height. Ignore air resistance:
a) If the initial speed of the ball is 4.4m/s, what is the speed when it hits the floor?
b) What initial speed should the ball have in order to bounce to thelevel of 6.40m above the ground?