Question

A ball is dropped from a height of 10 m. If the energy of the ball reduces by
40% after striking the ground, how much high can the ball bounce back?
(2)​

Answer 1

Answer:

6m

Explanation:

=10-(40/100*10)

=10-(4)

=6m

Answer 2

Explanation:

on reaching the ground the energy of the object = the energy at the top [law of conservation of mass]

energy at the top = potential energy = mgh

= m*10*10 = 100x joule [ let mass be x]

loss of energy = 40% of 100x J

energy left = 60% of 100x

= 60/100 * 100x = 60x

now the energy of the object on reaching the top again will be equal to that at the surface = 60x

bt height will differ

Ep = mgh = x*10*h

60x = 10xh

60x / 10x = h

h = 6 meter

:. the ball bounce back to 6m...