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I'm totally stumped!

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A skater spins with an angular speed of 12.0 rad/s with his arms outstretched. He lowers his arms, decreasing his moment of inertia from 41 kg·m² to 36 kg·m²

Calculate his initial and final rotational kinetic energy.

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Is the formula KE=1/2·I·ω² ?

ω=angular speed.. so ω=12.0 rad/s

so then how would i get I (inertia) ?

and how would i find out initial and final ?

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i just need some help :grumpy:

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# Homework Help: Rotational Equilibrium and Dynamics -

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