A heavy-rimmed bicycle wheel is set Figure P12.88 spinning in the direction shown in Figure P12.88. A string is tied to one end of the axle, and someone is holding up the string.

(a) Use torque arguments to explain why the wheel slowly revolves horizontally around the string end of the axle when the free end of the axle is released. (This effect is called precession.)

(b) The precession speed increases as time passes. Explain why.

Data from Figure P12.88