Ice skaters and angular momentum?

Question

Ice skaters use the conservation of angular momentum to produce high-speed spins when they bring their arms close to the rotation axis. Imagine a skater moves her arms inward, cutting the moment of inertia in half and therefore doubling the angular speed. If we consider the rotational kinetic energy, we see that the energy is doubled in this situation. Thus, angular momentum is conserved, but kinetic energy is not. Where does this extra energy come from?

Answer 1

The energy comes from the contraction of the skater muscles to bring their arms in. In terms of work, it is the work done pulling the arm mass against the centripetal force.

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Answer 2

FIRST i think of you are able to image if the skaters have equivalent mass then the midsection of mass i s the precise midsection of the pole so the rotation is relative to the midsection of the pole if one skater have been a million/2 the mass of the different say B is one 0.5 the mass of A then while B grabs the pole the midsection of mass isn't the midsection yet greater in the direction of the A skater... and for that reason the rotation may well be around that element... this might make the B skater look like hes vacationing in a distinctive direction then the A skater because of the fact the B skaters rotation may well be farther from the midsection of rotation.. angular velocity of the device might count near to reference and can merely i think of be the sum of the seperate mass's angular action..