- #1

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I was reading up on how to calculate I for various shapes on a website i often use and i understand their calc for a rod of length L but i don't get it for a sphere.

This page here http://hyperphysics.phy-astr.gsu.edu/hbase/isph.html#sph3

shows [tex] dI = \frac{y^2dm}{2}[/tex] and i don't know where the half comes from, can anyone explain?

Cheers

-G