A string that passes over a pulley has a 0.375 kg mass attached to one end and a 0.630 kg mass attached to the other end. The pulley, which is a disk of radius 9.50 cm, has friction in its axle. What is the magnitude of the frictional torque that must be exerted by the axle if the system is to be in static equilibrium?

How do you set up friction in the equation. Also, which direction would friction go?