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Wed 10 Sep, 2014 07:33 pm
Ice skater spinning in circle. Approximate body of skater is a cylinder of radius .25 m. Total mass of skater is 50 kg. When arms are extended, we attach 2 rods to the cylinder, the length is .75 m and the weight is 2.5 kg. When arms are together, she represents one cylinder.
What is the moment of inertia of skaters arms?
Moment of inertia of her body and arms?
Moment of inertia when her arms are clutched together close to her body (just a cylinder)?
Skater spins at a rate of 5 rad/s when arms are extended. What is angular velocity of skater when she brings her ams in?
Has the skater's energy increased decrased or stayed the same? What is the source of change?
@jasonmoon,
- Use
this website for the formulas for moment of inertia of various shapes.
- Remember that moments of inertia are additive.
- Energy is neither created or destroyed by moving her arms. Use the two moments you computed to find out how much her angular velocity increases when she pulls her arms in. Energy = 1/2 I w^2 where I in the moment of inertia, w is the angular velocity.
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