A circular disc A of radius r is made from an iron plate of thickness t and another circular disc B of radius 4r is made from an iron plate of thickness `t//4`. The relation between the moments of inertia `I_(A)` and `I_(B)` is (about an axis passing through centre and perpendicular to the disc)

Options

A. `I_(A) gt I_(B)`
B. `I_(A) = I_(B)`
C. `I_(A) lt I_(B)`
D. depends on the actual values of t and r

Answer

C

Explanation

`I=1/2Mr^(2) = 1/2(Ir^(2) omega)r^(2)` or `I propto tx^(4)`