A uniform cylinder whose mass is 50 kg and radius is 0.20 m is mounted so that it turns without friction on its axis, which is fixed. The cylinder is driven by a belt that wraps around its perimeter and exerts a constant torque. At t = 0, the cylinder's angular velocity is zero. At t = 20 s, its angular speed is 300 rev/min.
(a) What is the magnitude of the torque acting on the cylinder?
(b) What is the magnitude of the frictional force acting on the rim of the cylinder?