Question

A ball having initial velocity v is dropped from a height of 10 m. It loses 50% of its energy on striking the ground and rises to the same height after collision. What is the value of v.

Answer 1

$1 \div 2m {v}^{2} = mgh \: \\ {v}^{2} = 10 \times 10 \times 2 \\ {v}^{2} = 200 \\ v = 10 \sqrt{2} sec$