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 disturbed uniformly over the mop and if coefficient of friction between the mop and the floor is 
the torque applied by the machine on the mop is :
(a)
FR
(b)
FR/3
(c)
FR/2
(d)
FR/6
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 disturbed uniformly over the mop and if coefficient of friction between the mop and the floor is the torque applied by the machine on the mop is :
(a)
FR
(b)
FR/3
(c)
FR/2
(d)
FR/6
Question ID - 50226 | SaraNextGen Top Answer
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 disturbed uniformly over the mop and if coefficient of friction between the mop and the floor is the torque applied by the machine on the mop is :
(a)
FR
(b)
FR/3
(c)
FR/2
(d)
FR/6
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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 disturbed uniformly over the mop and if coefficient of friction between the mop and the floor is |
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(a) |
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(b) |
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(c) |
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(d) |
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Consider a strip of radius x 
thickness dx,
Torque due to friction on this strip.
=
.
correct answer is (a)