Question

A ball is allowed to fall from a height of 10 m. If there is 40%
loss of energy due to impact, then after one impact ball will
go up to
(a) 10 m (b) 8 m
(c) 4 m (d) 6 m

Answer 1

let the mass of the ball be "m"

h₁ = initial height before bounce for the ball = 10 m

initial potential energy before bounce is given as

PE₁ = mg h₁

h₂ = final height after bounce for the ball = ?

final potential energy after bounce is given as

PE₂ = mg h₂

Using conservation of energy

PE₂ = 60% of PE₁ (Since remaining 40% energy is lost)

mg h₂ = 0.60 mg h₁

h₂ = (0.60) (10)

h₂ = 6 m