Question

Moment of inertia of a uniform circular 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

Moment of inertia of disc about a diameter =$\frac{1}{4}MR^{2} = I$ (given) ∴ $MR^{2} = 4I$

Now moment of inertia of disc about an axis perpendicular to its plane and passing through a point on its rim

= $\frac{3}{2}MR^{2} = \frac{3}{2}(4I) = 6I$.