A small hard solid sphere of mass m and negligible radius is connected to a thin rod of length L and mass 2 \mathrm{~m}. A second small hard solid sphere, of mass M and negligible radius, is fired perpendicularly at the rod at a distance h above the sphere attached to the rod, and sticks to it. In order for the rod not to rotate after the collision, the second sphere should have a mass M given by
Answer Choices
A. M=m
B. M=1.5 m
C. M=2 m
D. M=3 m
E. Any mass M will work.
