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Q.
A ball is dropped from a height of 20 cm. Ball rebounds to a height of 10 cm. What is the loss of energy?
Work, Energy and Power
Solution:
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 = $ mgh_2 $
=10 mg.
Therefore, the loss in energy
$ \frac{initial\, energy - final\, energy}{initial energy} \times 100 $
= $ \frac{20mg - 10 mg}{20 mg}\times 100 $
=50%