PLEASE HELP!
A rubber ball is dropped on to flat ground from a height of 2m.
(a) Calculate how long it takes for the ball to first hit the ground.

(b)The ball loses 10% of its kinetic energy at each bounce. Calculate the time taken for the ball to come to rest.

Question

PLEASE HELP! 
A rubber ball is dropped on to flat ground from a height of 2m. 
(a) Calculate how long it takes for the ball to first hit the ground. 

(b)The ball loses 10% of its kinetic energy at each bounce. Calculate the time taken for the ball to come to rest.

anonymous · Answer

I did (a). I just need help with (b).

anonymous · Answer

(a) h=(1/2)g(t^2)   =>   t=sqrt(d/g)~sqrt(4/9.81)~0.639 seconds.
(b) Sounds like a trick question. KE will approach 0 as # of bounces->infinity.

abb0t · Answer

I saw a question similar to this. I think you have to find a geometric series using the fact that velocity is proportional to square root of KE? 
Time between successive bounces is proportional to rebound velocity, and time between successive bounces is double the time the ball takes to fall from it's highest point between those two bounces.