# How do I get this equation for period?

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?

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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.

D H
Staff Emeritus