Question

Moment of inertia of a uniform circuar disc about a diameter is I. Its moment of inertia about an axis perpendicular to its plane and passing through a point on its rim will be:

• A. 5 I
• B. 6 I
• C. 3 I
• D. 4 I.

Answer 1

Answer: (B)

6 I

Answer 2

$\frac { 1 } { 4 } M R ^ { 2 } = I \Rightarrow M R ^ { 2 } = 4 I$

Now required moment of inertia

= $\frac { 3 } { 2 } M R ^ { 2 } = \frac { 3 } { 2 } ( 4 I ) = 6 I$