Question-

-A large bell is hung from a wooden beam so it can swing back and forth with negligible friction. The center of mass of the bell is 0.50m below the pivot, the bell has mass 38.0kg , and the moment of inertia of the bell about an axis at the pivot is 20.0kg*m^2 . The clapper is a small, 1.8kg mass attached to one end of a slender rod that has length L and negligible mass. The other end of the rod is attached to the inside of the bell so it can swing freely about the same axis as the bell.

-What should be the length L of the clapper rod for the bell to ring silently-that is, for the period of oscillation for the bell to equal that for the clapper?