Swinging Holiday Fun A holiday ornament in the shape of a hollow sphere with a mass of 20 grams and a radius of 4.9 cm is hung from a tree limb by a small loop of wire attached to the surface of the sphere. If the ornament is displaced a small distance and released, it swings back and forth as a physical pendulum. You can ignore any possible friction at the pivot.

What is the rotational inertia for the hollow spherical ornament about the pivot at the tree limb? The rotational inertia for a hollow sphere about its center of mass is 2/3MR².