Q. 15 Why does a solid sphere have a smaller moment of inertia than a hollow cylinder of the same mass and radius, about an axis passing through their axes of symmetry?
Hint: Use moment of inertia, I=Σmir2i.
Step 1: Interpret the answer.
The moment of inertia of a body is given by I=Σmir2i [sum of moment of inertia of each constituent particles]
All the mass in a cylinder lies at distance R from the axis of symmetry but most of the mass of a solid sphere lies at a smaller distance than R.