# A body falling from the height of 10m rebounds from a hard floor. It loses 20% of its energy in input. What is the height to which it would rise after the impact?

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by kaushikabhi

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by kaushikabhi

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At h = 10m,

PE = mgh = 10mg

KE = 0,

Total Energy (TE) = 10mg

Just before impact,

PE = 0

KE = TE - PE = 10mg

After impact, energy lost = 20%

energy lost = 20% of 10mg = 2mg

Total Energy Left (TE)= 10mg - 2mg = 8mg

Let after impact it reaches a maximum height = H

At height H

KE = 0 (as velocity is 0 at maximum height)

PE = mgH

But PE = TE = 8mg

Thus mgH = 8 mg

or**H=8m**

PE = mgh = 10mg

KE = 0,

Total Energy (TE) = 10mg

Just before impact,

PE = 0

KE = TE - PE = 10mg

After impact, energy lost = 20%

energy lost = 20% of 10mg = 2mg

Total Energy Left (TE)= 10mg - 2mg = 8mg

Let after impact it reaches a maximum height = H

At height H

KE = 0 (as velocity is 0 at maximum height)

PE = mgH

But PE = TE = 8mg

Thus mgH = 8 mg

or