Q. Moment of inertia of a uniform circular disc about a diameter is $I$. Its moment of inertia about an axis $\bot$ to its plane and passing through a point on its will be
A) $5I$
B) $3I$
C) $6I$
D) $4I$
Explanation
(c) Moment of inertia of uniform circular disc about diameter $= I$
According to theorem of perpendicular axes,
Moment of inertia of disc about its axis $= 2I\left( = \frac{1}{2}mr^{2} \right)$
Applying theorem of parallel axes
Moment of inertia of disc about the given axis
$= 2I + mr^{2} = 2I + 4I = 6I$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.