Conceptual Check on Rolling Friction.
I. Rolling friction is generally much smaller than sliding friction.
II. A wheel rolling on a horizontal surface slows down due to the deformation of the surface and wheel at the contact point.
III. If a disc rolls up an incline, static friction acts up the incline to assist rotation.
IV. If a disc rolls down an incline, static friction acts up the incline to provide opposing torque.
V. For a hollow sphere rolling down an incline, the friction force required is less than that for a solid sphere of same mass.
