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A body of mass 'm is drhopped from a hei...

A body of mass 'm is drhopped from a height 'h'. The speed with which body hits the ground is `sqrt(0.9gh)` Find the work done by air-resistance furing its fall.

Text Solution

Verified by Experts

The work done by weight
`W_(mg)=+mgh`
Let work done by air-resistance is `W_(f)`
By work energy theorem,
`W_(mg)+W_(f)=1/2mv^(2)-0`
`mgh+W_(f r) =1/2m(0.9gh)-0`
`impliesW=-0.55mgh`
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