Like the linear kinetic energy calculation, the rotational one requires us to know the section inertia properties to be able to calculate how much there really is. Much like the linear version, the rotational speed is squared, so rotational velocity counts for a bunch of the energy difference the same way.
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If we looked at the units to run this in Imperial, you would never again ask why engineers like to run the math in KMS (metric). Lucky for us, some of the companies do the mass properties math for us, but you have to dig or beg for those values.