The kinetic energy of a solid body rotating around an axis is proportional to
the square of the angular velocity: K = Jω2. The coefficient J is called the
2
moment of inertia relative to a given axis. Find the moment of inertia for a
dumbbell that represents point masses m and m at the ends of a light rod,
1 2
if its axis of rotation is perpendicular to the rod and is at a distance r and r
1 2
from the point masses.