Question

A ball is dropped from a height of 5m on to a sandy floor and penetrates the sand 10 cm before coming to rest . Find the retardation of the ball assuming it to be uniform.

Answer 1

Use the equations of motion:

v²-u² = 2as

Final vel = v = 0

Initial vel = u = √(2g*5) = √(10g)------ {this is obtained by initial vel=0 as droped from a ht, final vel is what u have to determine, height s = 5 mt and accn due to gvt = g, so u²-0=2*g*h or u=√(2gh)}

So 0-10g = 2(a)*(10/100)

So a = -50g.

So retardation is 50*g = 500ms^-2.

Hope that helps.