Question

A pendulum is made from a long rod of mass M and length L with a solid sphere (ball) of mass m and radius R attached to one end. As measured from the top of the pendulum (the end of the rod without the sphere), how far down the rod is the center of mass of the pendulum located

Answer 1

Step-by-step explanation:

If we assume the rod and sphere are of uniform construction so that their individual centers of mass are at their geometric centers, and that the rod end is attached to the surface of the sphere.

Balance moments about the rod free end of the assembly with its parts

(M + m)Cx = M(L/2) + m(L + R)

Cx = (M(L/2) + m(L + R)) / (M + m)