Halliday, Resnick & Walker — Rolling, Torque, and Angular Momentum: Problem 39

39 The angular momentum of a flywheel having a rotational inertia of $0.140 \text{ kg}\cdot\text{m}^2$ about its central axis decreases from $3.00$ to $0.800 \text{ kg}\cdot\text{m}^2/\text{s}$ in $1.50 \text{ s}$. (a) What is the magnitude of the average torque acting on the flywheel about its central axis during this period? (b) Assuming a constant angular acceleration, through what angle does the flywheel turn? (c) How much work is done on the wheel? (d) What is the average power of the flywheel?