Question

A rubber ball falling from a height of 5 m rebounds from a hard floor to a height of 3.5 m. The percentage loss of energy during the impact is

• A. $20\%$
• B. $30\%$
• C. $43\%$
• D. $50\%$

Answer 1

The correct option is B $30\%$

Loss of Kinetic Energy is given by:
$\%LossofK.E.=\frac{h_1-h_2}{h_1}\times 100$

Here, $h_1=5m$, $h_2=3.5m$

$\Rightarrow \%LossofK.E.=\frac{5-3.5}{5}\times 100=\frac{1.5}{5}\times 100=30\%$