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Question: Consider a flywheel made of iron, with a density of 7800 , in the shape of a uniform disk with a thickness of 12.4 . What would the diameter of such a disk need to be if it is to store an amount of kinetic energy of 14.6 when spinning at an angular velocity of 91.0 about an axis perpendicular to the disk at its center?

I know that I=.5mr^2 for the disk, I just don't know how to apply that towards getting a solution for work?

I have pondered this question for some time now, and I know im just missing one piece, i just don't know what it is. Any help would be greatly appreciated. Thanks

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# Diameter of disk?

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