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imagine a disk rotating by an axis that passes through the center of the disk

how can we find the analogue of a mass rotating by an axis?

I mean, how can we lump the whole mass of the wheel to a point?

how much will be the distance of this point from the axis?

for example to rotate a disk with radius 10 and mass 100 you need the same force as to rotate a point of mass 100 and rotation radius = ??

I suppose the radius will be some less than 10 (since not all parts of the disk are at this radius), but how much exactly?

thanks

PS: we need to do this in order to calculate other things, eg angular acceleration, etc

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# Lump disk mass to a point

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