- #1
BradP
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Homework Statement
This is not a homework question but it could be. I am trying to understand why the moment of inertia of a thin disc about its axis of rotation is 1/2 MR2.
Homework Equations
The rotational moment of inertia of a system of points is [tex]^{}\sum[/tex]mr2.
The Attempt at a Solution
However, if you just took one point at radius r and divided its mass into as many points as it took to make a virtual ring with radius r, the result of [tex]^{}\sum[/tex]mr2 is mr2, right? So how is this the equation for a solid disc and not a thin ring?