Question

a ball is dropped on to a floor .if thecoffecient of restitution is 0.5 the percentage loss of energy of theball on rebounding from the floor is

Answer 1

Velocity when it hits the ground
u1 = sqrt(2gH)

Velocity when after just hitting the ground
v1 = sqrt(2gH’)

e = (v2 - v1) / (u1 - u2)
0.5 = (0 - v1) / (u1 - 0)
u1 = -2v1
H = 2H’ ……[from above equations]
H’ = H/2

Initial potential energy = mgH
Final potential energy = mgH’ = mgH/2

Loss in energy = mgH - mgH/2 = mgH/2

% Loss in energy = [(mgH/2) / mgH] * 100
= 50%