Question

The moment of inertia of a thin circular disc about an axis passing through its centre and perpendicular to its plane is $I$. Then, the moment of inertia of the disc about an axis parallel to its diameter and touching the edge of the rim is

• A. $I$
• B. $2I$
• C. $\frac{3}{2}I$
• D. $\frac{5}{2}I$

Answer 1

The correct option is D $\frac{5}{2}I$

Moment of inertia of a circular disc about an axis passing through centre of gravity and perpendicular to its plane
$I=\frac{1}{2}M{R}^2$ ......(i)
From equation (i) $M{R}^2=2I$
Then, moment of inertia of disc about tangent in a plane $=\frac{5}{4}M{R}^2$
$=\frac{5}{4}\left(2I\right)$
$=\frac{5}{2}I$