Problem: A person stands, hands at his side, on a platform that is rotating at a rate of 1.30 rev/s. If he raises his arms to a horizontial position the speed of rotation decreases to 0.80 rev/s. (a) Why? (b)By what factor has the moment of inertia changed?(adsbygoogle = window.adsbygoogle || []).push({}); Answer: (b) 1.6

Okay, so I know part a which is because his rotational inertia increases.

Someone please help explain where 1.6 is even coming from... I have yet to get a soild answer. :(

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# Homework Help: Angular Mometum please help.

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