A Ferris wheel rotates because a motor exerts a torque on the wheel. The radius of the London Eye, a huge observation wheel on the banks of the Thames, is 67.5 m and its mass is 1.90 × 10 6 kg. The cruising angular speed of the wheel is 3.50 × 10−3 rad/s.
(a) How much work does the motor need to do to bring the stationary wheel up to cruising speed? [Treat the wheel as a hoop.]
(b) What is the torque (assumed constant) the motor needs to provide to the wheel if it takes 20.0 s to reach the cruising angular speed?