Question

Three particles (each of mass $10g$) are situated at the three corners of an equilateral triangle of side $5cm$. Determine the moment of inertia of this system about an axis passing through one corner if he triangle and perpendicular to the plane of the triangle.

Answer 1

Moment of inertia due to mass passing through the axis is zero. 
Moment of inertia due to other two mass=

$2m{r}^2=2\times {10}^{-2}\times 25\times {10}^{-4}=5\times {10}^{-5}Kg{m}^2$