Question

A ball is dropped from the top of a vertical cliff 45m high. Given that the velocity just before striking the sandy beach is 30m/s, and the ball penetrate the sand to a depth of 10cm determine its average retardation.

Answer 1

v² = u² + 2as 
O² = 900² + 2 x a x 0.10
-900 = 0.20 a
a = ^(-900)/_0.20
a = -450 m/s²