Question

The radius of gyration of a thin uniform circular disc (of radius $R$) about an axis passing through its centre and lying in its plane is

• A. $ R $
• B. $ \frac{R}{\sqrt{2}} $
• C. $ \frac{R}{4} $
• D. $ \frac{R}{2} $

Answer 1

Answer: (D)

In case of a disc rotating about an axis through its centre of mass and parallel to its plane
$K=\sqrt{\frac{I}{M}}=\sqrt{\frac{\left(\frac{1}{4}\right) M R^{2}}{M}}$
$=\frac{R}{2}$