Question

An axle consists of a rotating disk of radius 30.5 cm centered
about a rod of radius 12.7 cm, as shown. The rotation of the axle is
controlled by a pulling force (ccw) and dragging force (cw). The
designer is worried about the presence of friction between the rod
and disk. When the pull force is 25.0 N and a drag force is 12.0 N, the
net torque on the disk is 3.33 Nm in the ccw direction. Determine the
magnitude of the average frictional force acting on the disk.

12.7 cm 30.5 cm ----Fdrag

Answer 1

Net torque = summation Fr

3.33 = Fpull*0.305 - Fdrag*0.305 -Ff*0.127

3.33 = 25*0.305 - 12*0.305 -Ff*0.127

Ff = 5 N answer