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A cylindrical massless cord of length l=...

A cylindrical massless cord of length `l=10cm` and radius `r=3cm` is slowly extracted from the neck of a bottom opened bottle. If the normal pressure between the botle and un-extracted part of the cork at any instant is constant and equal to `P=(10^(5))/(pi)N//m^(2)`, find the work done (in Joule) in extracting it completely. The coefficient of friction between the cork and bottle is `mu=0.3`

Text Solution

Verified by Experts

The correct Answer is:
9
`W=int_(0)^(l) mu 2pi r x dx P`
`=pimurPl^(2)`
`=pi(0.3)(3xx10^(-2))(10^(5))/(pi)xx10^(-2)=9J`
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