# Moment of inertia of a square

1. Jul 24, 2013

### duplaimp

1. The problem statement, all variables and given/known data
There are four masses (particles) with a mass of 30gr each and they are at the vertices of a square that has each side with a length of 90cm.
What is the moment of inertia of this system through a perpendicular axis that is at the center of the square?

3. The attempt at a solution
My idea is to use the moment of inertia $I = mr^{2}$ (Point mass m at a distance r from the axis of rotation.)
Then the distance will be the hypotenuse of a right triangle that has each side with 45cm and putting that into the moment of inertia and multiply by 4

Is this correct?

2. Jul 24, 2013

### Filip Larsen

Yes, that is correct.

3. Jul 25, 2013

Thank you