The mass of a body cannot be considered to be concentrated at the centre of mass of the body for the purpose of computing its moment of inertia.
For then the moment of inertia of every body about an axis passing through its centre of mass would be zero.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false
D. If both assertion and reason are false.

Answer

A

Explanation

(a) Moment of inertia is then sum of `m r^2` terms. We cannot change all the `r' s`, keep `m's` the same, and expect `Sigma m_i r_i^2` to remain unchanged.