Anyone good at physics or engineering?

普渡哥

We wrap a light, flexible cable around a thin-walled, hollow cylinder with
mass M and radius R. The cylinder is attached to the axle by spokes of a
negligible moment of inertia.The cylinder rotates with negligible friction
about a stationary horizontal axis. We tie the free end of the cable to a
block of mass m and release the object with no initial velocity at a
distance h above the floor. As the block falls, the cable unwinds without
stretching or slipping, turning the cylinder. The speed of hanging mass m
just as it strikes the floor is v=sqrt 2mgh/(m+M). Use energy concepts to
explain why the answer to part A is different from the speed found in case
of solid cylinder,which is
v= sqrt 2gh/(1+M/2m) ?????