Question

A ball is dropped from a height of $10m$. If the energy of the ball reduces by $40\%$ after striking the ground, how much high can the ball bounce back? $(g=10m{s}^{-2})$ :

• A. $6m$
• B. $4m$
• C. $10m$
• D. None of the above

Answer 1

The correct option is A $6m$

$Mgh=M\times 10\times 10=100MJ.$
Energy is reduced by $40\%$ then the remaining energy is $60MJ$.
Then, $60M=M\times 10\times h^{\prime }$

or, $h^{\prime }=6m$