A passenger bus in Zurich, Switzerland, derived its motive power from the energy stored in a large flywheel. The wheel was brought up to speed periodically, when the bus stopped at a station, by an electric motor, which could then be attached to the electric power lines. The flywheel was a solid cylinder with mass 1000 kg and diameter 1.80 m; its top angular speed was 3000 rev/min. (a) At this angular speed, what is the kinetic energy of the flywheel? (b) If the average power required to operate the bus is 1.86 × 104 W, how long could it operate between stops?
Solution 86P Problem (a) Step 1: To calculate Kinetic Energy K Mass of the cylinder M = 1000 Kg Diameter of the cylinder D = 1.80 m Radius R = 0.9 m Angular speed = 3000 rev/min