Chapter 10, Problem 79P

To determine

To show:

a) That rotational inertia of a solid cylinder of mass M and radius R about its central axis is equal to the rotational inertia of a thin hoop of mass M and radius $R/\surd 2$ about its central axis.

b) That the rotational inertia I of any given body of mass M about any given axis is equal to rotational inertia of an equivalent hoop about that axis, if the hoop has the same mass M and radius k given by $k= \sqrt{\frac{I}{M}}$