Question

A ball is dropped from a height of $10\text{m}$. Ball rebounds to a height of $5\text{m}$. What is % loss of energy?

• A. $20$%
• B. $30$%
• C. $40$%
• D. $50$%

Answer 1

The correct option is D $50$%

As ball is dropped from height of $10\text{m}$.
Kinetic enegry of ball just before collision ;$K_i=mg{h}_i=10mg$
After collision, ball reaches maximum height of $5\text{m}$.
Kinetic energy of ball just after collision ;$K_f=mg{h}_f=5mg$
% loss of energy during collision$=\frac{K_i-K_f}{K_i}\times 100$
$=\frac{10mg-5mg}{10mg}\times 100$
$=50$%