Please help :)
Kevin drops a 75 g “bouncy ball” out his second floor window, which is 8.0 m above the hard ground (pavement). He noticed that the ball bounced back up to a height of 6.1 m above the ground.

a) How much kinetic energy did the ball have just after it hit the ground (and bounced up again).

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".