Posted by Tarren on Thursday, December 2, 2010 at 1:17pm.
A skater spinning with angular speed of 1.5 rad/s draws in her outstretched arms thereby reducing her moment of inertia by a factor a 3.
a) Find her angular speed.
b)What is the ratio of her final angular momentum to her initial angular momentum?
c)Did her mechanical energy change? (Yes but why?)

Physics  Tarren, Thursday, December 2, 2010 at 1:19pm
I forgot to add one more part.
d) Determine the ratio of her final kinetic energy to her initial kinetic energy.

Physics  drwls, Thursday, December 2, 2010 at 2:26pm
I*w stays the same due to the requirement for angular momentum conservation.
If I is cut in half, w must double.
KE is (1/2)I*w^2 = (1/2)(I*w)^2/I
Since I drops by half while I*w is constant, the kinetic energy must also double.
The extra KE comes from work done by the skater pulling in her arms. There is a lot of centrifugal resistance.
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