Question

A ball is dropped from a height of 20 cm. Ball rebounds to a height of 10 cm. What is the loss of energy?

• A. 25%
• B. 75%
• C. 50%
• D. 100%

Answer 1

Answer: (C)

Since ball is at a specific height it possess potential energy
= mgh
where m is mass, g is gravity and h is height
Initial energy of ball = mg $h_1$
= 20 mg
Final energy of ball = $mg{h}_2$
=10 mg.
Therefore, the loss in energy
$\frac{initialenergy-finalenergy}{initialenergy}\times 100$
= $\frac{20mg-10mg}{20mg}\times 100$
=50%