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A man is rowing a boat with a constant v...

A man is rowing a boat with a constant velocity `v_(0)` in a river. The contact area of boat is `'A'` and coefficient of viscosity is `eta`. The depth of river is `'D'` . Find the force required to row the boat.

Text Solution

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`F_(ext)-F_(v)=ma_(res)`
As boat moves with constant velocity `a_(res)=0`
But `F_(v)=etaA(dv)/(dz),`but`(dv)/(dz)=(v_(0)-0)/(D)=(v_(0))/(D)`
then `F_(ext)=F_(v)=(etaAv_(0))/(D)`
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