Four point masses, each of value m, are placed at the corners of a square ABCD of side l. The moment of inertia of the is system about an axis passing through A and parallel to BD is

Options

A. `2 ml^2`
B. `sqrt(3) ml^2`
C. `3 ml^2`
D. `m l^2`

Answer

C

Explanation

The situation is shown in figure.
`I_(x x') = m xx DP^2 + m xx BQ^2 + m xx CA^2`
=`m xx 2 xx ((sqrt(2) l)/(2))^2 + m xx (sqrt(2) l)^2`
=`3 m l^2`.