A turntable is driven by a small motor that provides a constant driving torque of 0.30 N·m. Because of friction in the bearings, a resistive torque of 0.10 N·m always acts opposite the direction of rotation.
Starting from rest, the motor is switched on and allowed to rotate the turntable through exactly 8.0 full revolutions.
(a) Determine the net external torque acting on the turntable while the motor is running. Clearly indicate the direction of the net torque relative to the motion.
(b) Calculate the net mechanical work done on the turntable during the 8.0-revolution interval.
(c) Suppose the motor is switched off immediately after the turntable has completed the 8.0 revolutions. Qualitatively describe what happens to the turntable’s kinetic energy as it continues to rotate under the influence of friction only. Explain your reasoning without using numerical values.