Suppose the solid cylinder in the apparatus descended in Example 9.9 (Section 9.4) is replaced by a thin-walled, hollow cylinder with the same mass M and radius R. The cylinder is attached to the axle by spokes of a negligible moment of inertia.
(a) Find the speed of the hanging mass m just as it strikes the Door.
(b) Use energy concepts to explain why the answer to part (a) is different from the speed found in Example 9.9.