Problem: A ring pendulum is a steel ring of mass M whose thickness is very small compared to its radius R. It is suspended on a knife edge, displaced, and the time for ten cycles is measured. What period can be expected?

Solution: The period of a physical pendulum requires the moment of inertia I and the distance d from the suspension point to the center of mass (CM) (see Figure 13.11, page 374):

Substituting these into the formula for the period...