a body falling from a height of 10m rebounds from a hard floor.It loses 20% of its energy in the impact.What could be the height to which it would rise after the impact

Given that the body is dropped from a height, h₁ = 10 m

Potential energy at h₁ = mgh₁

Given g =10 m/s² , h₁ = 10 m

Therefore the potential energy at h₁ = m×10×10

 = 100m J

On striking the ground level, the ball looses 20% of its initial energy:

i.e. (20/100)× 100m J

=20m J

The energy left on striking the ground = 100 m J - 20 m J

= 80 m J

So the final energy of the ball , mgh₂ = 80m J

i.e h₂ = (80 /10) 

        = 8 m

Hence the body will bounce back to a height of 8 m after the impact.