Question

Three point size bodies of masses $10,20$ and $30g$ are attached at three corners of light equilateral triangular frame. If their moment of inertia about an axis passing through two lighter particles is $1500gc{m}^2$, their moment of inertia about an axis passing through two heavier particles is :

• A. $3000gc{m}^2$
• B. $1500gc{m}^2$
• C. $750gc{m}^2$
• D. $500gc{m}^2$

Answer 1

The correct option is D $500gc{m}^2$

Let the side of triangle be $l$

Height of equilateral triangle $h=\frac{\sqrt{3}l}{2}$

Moment of inertia about an axis passing through two lighter particles , $I=1500=30h^2$

Moment of inertia about an axis passing through two heavier particles $I_1=10h^2=1500/3=500gc{m}^2$