I recently had a question on a test that just boggled my mind. I could not find the answer and unfortunatley could not consult a T.A. I have a vague memory of the question. It is a figure skater rotating at angular velocity w = 2 rad/s (not sure if that number is correct). The figure skater is holding a sphere mass 150grams(.15kg) which is located .6 meters from the axis of rotation. The sphere is 1.6m from the ground.(adsbygoogle = window.adsbygoogle || []).push({});

a) What is the net force acting on the small sphere? (I said gravity but was not sure)

b) How long will it take the ball to hit the ground if released?

c) Calculate the Initial Kinetic Energy given the final Kinetic engery is 12000 J. (I think this was the phrasing of last question)

At first I thought of using the

mgh + 1/2I(Inertia)w(Angular vel)^2 = 1/2mv^2(1+ I(Intertia of Centre of Mass) / MR^2)

We are not given intertia though? or did i remember this incorrectly perhaps? Would it make more sense to have intertia?

I am truley stumped, any help would be awesome.

Kevin

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# Homework Help: Questions dealing with Angular momentum (but maybe kinetic engery)

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