Question

The moment of inertia of a uniform circular disc of radius ${}^{\prime }{R}^{\prime }$ and mass ${}^{\prime }{M}^{\prime }$ about an axis passing from the edge of the disc and normal to the disc is

• A. $M{R}^2$
• B. $\frac{1}{2}M{R}^2$
• C. $\frac{3}{2}M{R}^2$
• D. $\frac{7}{2}M{R}^2$

Answer 1

The correct option is C $\frac{3}{2}M{R}^2$

M.I of a uniform circular disc of radius ${}^{\prime }{R}^{\prime }$ and mass ${}^{\prime }{M}^{\prime }$ about an axis passing through C.M. and normal to the disc is
$I_{C.M}=\frac{1}{2}M{R}^2$

From parallel axis theorem
$I_T=I_{C.M}+M{R}^2=\frac{1}{2}M{R}^2+M{R}^2=\frac{3}{2}M{R}^2$