Q. 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
Explanation
(b) Moment of inertia of circular ring about an axis passing through its centre of mass and perpendicular to its plane
$I = MR^{2}$
Here, $I = 4\ kg - m^{2},\ m = 1\ kg$
$R^{2} = \frac{4}{1} = 4$
or $R = 2$m
Therefore, diameter of ring = 4 m.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.