Medium· Moment of Inertia (Moment of Inertia of Some Important Cases)· +4 / −1
A solid sphere of radius and mass is attached at a point to a smaller solid sphere of radius and mass . Assume that the line joining their centres lies along the horizontal. The moment of inertia of the system calculated about a vertical axis passing through the centre of is and that calculated about a vertical axis passing through the centre of is . The difference is:
Figure: the two touching spheres, drawn twice; on the left the vertical axis passes through the centre of (giving ) and on the right through the centre of (giving ). The centres are a distance apart.
