Q. Three point masses, each of mass $m$ are placed at the corners of an equilateral triangle of side $l$. Moment of inertia of this system about an axis along one side of triangle is
A) $3\ ml^{2}$
B) $\frac{3}{2}ml^{2}$
C) $ml^{2}$
D) $\frac{3}{4}ml^{2}$
Explanation
(d) Distance of corner mass from opposite side
$r = \sqrt{l^{2} - (l/2)^{2}} = \frac{\sqrt{3}}{2}l$
$I = mr^{2} = \frac{3}{4}ml^{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.