# How do I get this equation for period?

1. Apr 2, 2008

### frasifrasi

In class, we were asked to the relation T =2π√(2I/mgL).

However, I am only able to get T =2π√(I/mgL) -- I have no idea where that 2 came from. This is for a physical pendulum of a rod like object swinging back and forth.

Does anyone know how to get that equation?

2. Apr 2, 2008

### Snazzy

From what I know, you are right that $$T = 2\pi \sqrt{\frac{I}{mgL}}$$

I don't know where that extra 2 came from either.

3. Apr 2, 2008

### D H

Staff Emeritus
It would have helped a lot if you had used the template. What exactly is the problem to be solved here? About what point is the inertia measured? What work have you done to arrive at a solution?