Question

a ball is dropped from a height of 20m and rebounds back up to the height of 3m calculate its kE when it strikes the ground

Answer 1

And with thanks.

v ^2 = 2gh.

Square of the ground velocity is proportional to height from which it is dropped.

h/20 = (3/4)^2

h= 11.25 m

Using h = 0.5 g t^2

t^2 = 2*11.25/9.8

t = 1.515s ( time to go up after the first bounce)

time to fell down , is also 1.515 s m

Time between first and second bounce is 2*1.515 = 3.03 s.

Answer 2

Answer:

15ms is the answer

Explanation:

Hope it is helpful