Question

The radius of gyration of a solid sphere of radius $R$ about a certain axis is also equal to $R$. If $r$ is the distance between the axis and the centre of the sphere, then $r$ is equal to:

• A. $R$
• B. $0.5R$
• C. $\sqrt{0.6}R$
• D. $\sqrt{0.3}R$

Answer 1

The correct option is C $\sqrt{0.6}R$

The radius of gyration of a solid sphere of radius $R$ about a certain axis is equal to $R$.

$k=R$

$M{k}^2=M{R}^2$

$I=I_{cm}+m{r}^2$

$M{R}^2=\frac{2}{5}M{R}^2+M{r}^2$

$r^2=\frac{3}{5}{R}^2$

$r=\sqrt{0.6}R$

The correct option is C.