A rubber ball falls on a floor from a height of `19*6m. ` Calculate the velocity with which it strikes the ground. To what height will the ball rebounce if it loses `25%` of its energy on striking the ground?

Explanation

Here, `h_(1)=19*6m, v_(1)=?` Loss of energy `=25% h_(2)=?`
On striking th egroun, K.E. `=` P.E
`(1)/(2)mv_(1)^(2)=mgh_(1)`
`v_(1)=sqrt(2gh_(1))=sqrt(2xx9*8xx19*6)=19*6m//s`
As the body loses `25%` of its energy, final energy `E_(2)=(75)/(100)` of initial energy
i.e., `mgh_(2)=(75)/(100)(mgh_(1))` `(h_(2)=(3)/(4)h_(1)=(3)/(4)xx19*6=14*7m`