Question

Three particles each of mass $M$ are placed at the corners of a triangle of side length $L$. About an axis passing through any side of frame the moment of inertia of three bodies is :

• A. $M{L}^2$
• B. $\frac{3M{L}^2}{2}$
• C. $\frac{3M{L}^2}{4}$
• D. $\frac{3M{L}^2}{5}$

Answer 1

The correct option is C $\frac{3M{L}^2}{4}$

MI of system about a side will have contribution from the only mass which does not lie on this axis.
$I=M(\frac{\sqrt{3}}{2}L{)}^2$
$=\frac{3}{4}M{L}^2$