Question

Three point masses, each of mass $m$ are placed at the corners of an equilateral triangle of side The moment of inertia of this system about, an axis along one side of the triangle is

• A. $ 3\,m{a}^{2} $
• B. $ 2\,m{a}^{2} $
• C. $ \frac{3}{4}m{a}^{2}$
• D. $ \frac{3}{2}m{a}^{2} $

Answer 1

Answer: (C)

Moment of inertia of system about side $A B$ is

$I=m(0)^{2}+m(0)^{2}+m\left(\frac{\sqrt{3}}{2} a\right)^{2}$
$=\frac{3}{4} m a^{2}$