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To mop-clean a floor, a cleaning machine...

To mop-clean a floor, a cleaning machine presses a circular mop of radius R vertically down with a total force F and rotates it with a constant angular speed about its axis. If the force F is distributed uniformly over the mop and the floor is `mu`, the torque, applied by the machine on the mop is : a) `muFR//3` b) `muFR//6` c) `muFR//2` d) `(2)/(3)muFR`

A

`2/3 mu FR`

B

`mu FR//3`

C

`muFR//2`

D

`muFR//6`

Text Solution

Verified by Experts

The correct Answer is:
A
`dt = (df).x`
`= (muN)x`
`=mu F/(piR^(2)). 2pi x dx.x`
`=(2muF)/R^(2) x^(2) dx`
`tau = (2muF)/(3R^(2)) R^(3) = (2mu FR)/3`
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