Finding the Period of a Physical Pendulum Attached to a Solid Sphere

[jboone88]

I can't figure this one out:

A point of the surface of a solid sphere (radius = R) is attached directly to a pivot on the ceiling. The sphere swings back and forth as a physical pendulum with a small amplitude. What is the length of a simple pendulum that has the same period as this physical pendulum? Give answer in terms of R.

Thanks for the help

 

[Hootenanny]

Well, how far have you got?