- #1
Lorens
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I was reading this in http://en.wikipedia.org/wiki/Moment_of_inertia
I can not understand, why would the mass become more concentrated around the rotation axis just because they move there arms, what have i missed? ...
Kindly Paul-Martin
This formula explains the speeding up of ice skaters when they pull in their arms. Since the ice is nearly frictionless, the kinetic energy should stay constant during their spin. When they pull in their arms, the skaters decrease their moment of inertia I (their mass is more concentrated close to the rotation axis). To keep the kinetic energy constant, the angular velocity ω must increase; hence, the skaters spin faster.
I can not understand, why would the mass become more concentrated around the rotation axis just because they move there arms, what have i missed? ...
Kindly Paul-Martin