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A body dropped from a height H reaches t...

A body dropped from a height H reaches the ground with a speed of 1.2 `sqrt(gH)`. Calculate the work done by air friction.

A

`-mgh`

B

`mgh `

C

`-(mgh)/(2)`

D

`(mgh)/(2)`

Text Solution

Verified by Experts

The correct Answer is:
C
Identify initial and final state and identify all forces
`W_(g)+W_("air res.")=DeltaK`
`mgh+W_("air res")=(1)/(2)m(sqrt(gh))^(2)-0`
`implies W_("air res.")=-(mgh)/(2)`
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