Question

The moment of inertia of a circular ring of mass $1\,kg$ about an axis passing through its centre and perpendicular to its plane is $4\, kg-m^{2}$ . The diameter of the ring is

• A. 2 m
• B. 4 m
• C. 5 m
• D. 6 m

Answer 1

Answer: (B)

4 m

Answer 2

Moment of inertia of circular ring about an axis passing through its center of mass and perpendicular to its plane
$I=M R^{2}$
here $I=4\, k g-m^{2}$
$m =1\, kg$
$=R^{2}=\frac{4}{1}=4 R=2\, m$
Therefore, diameter of ring $=4\, m$