Q. Moment of inertia of a disc about a diameter is $I$. Find the moment of inertia of disc about an axis perpendicular to its plane and passing through its rim?
A) $6\ I$
B) $4\ I$
C) $2\ I$
D) $8\ I$
Explanation
(a) Moment of inertia of a disc about a diameter is
$\frac{1}{4}\ MR^{2} = I$ (given)
$\therefore$ $MR^{2} = 4I$
Now, required moment of inertia $= \frac{3}{2}MR^{2}$
$= \frac{3}{2}(4I) = 6I$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.