Question

a ball is dropped from rest at a height of 12m.if it loses 25% of kinetic energy on striking the ground, what is the height to which it bounces?

Answer 1

Answer:

gain is 75 •/•

=> 3/4 × 120 m = 90m

90m = mgh

h=90/g

h=90/10

h=9m.

Answer 2

Answer:

Explanation:

Given : height = 12m

            Kinetic energy = 25%, Potential energy = 75%

             When a ball is dropped from a height, the potential energy changes to kinetic energy.

Mgh = (final kinetic energy)

120M = (final K.E.)

Ball loses 25% of (final K.E.),

so initial energy with which it bounces back = 75% of (final K.E)  

= (3/4) × 120M = 90M.

90M = Mgh

H= 9 metres.

There was a kinetic energy loss because we know when the ball bounces, it'll create some sound, heat, and vibrations on the floor, so the 25% of kinetic energy is lost.