Question

A ball is dropped from a height of $20cm$. If the ball rebounds to a height of $10cm$. What will be the loss of energy?

• A. Loss in energy of the ball is $3$
• B. Loss in the energy of the ball is $4$
• C. charge in total mechanical energy of the ball is $1.5$
• D. The momentum of the ball at top most point is zero

Answer 1

The correct option is C charge in total mechanical energy of the ball is $1.5$

Let

$H_1=$ Initial height before drop $=20cm$

$H_2=$ Initial height after dropping $=10cm$

As energy is loss, so potential energy after dropping will be fraction of initial potential energy.

Potential energy before dropping $=mg{h}_1$

$=mg\left(20\right)$

Potential energy after dropping $=mg{h}_2$

$=mg\left(10\right)$

According to above statement -

$\Rightarrow mg\left(10\right)=Xmg\left(20\right)$

$X=\frac{10}{20}=\frac{1}{2}$

Hence, $50\%$ energy is lost.