Angular momentum/kinetic energy

[twituksh12345]

Homework Statement

An ice skater holds two weights in his outstretched hands and rotates about his vertical axis. Then he brings the weights closer to his hands.In accordance with the law of conservation of angular momentum,the angular velocity of the ice skater increases.But so does the rotational kinetic energy.Where does this extra energy come from?

Homework Equations

The Attempt at a Solution

 

[rl.bhat]

The muscles in his hands do work on the weights to bring them closer. this will increase the rotational kinetic energy.

 

[nlightner]

This extra energy comes from the conversion of potential energy into kinetic energy. As the weights are brought closer to the skater's hands, the potential energy of the system decreases. This decrease in potential energy is then converted into an increase in rotational kinetic energy, causing the skater's angular velocity to increase. This is in accordance with the law of conservation of energy, which states that energy cannot be created or destroyed, only converted from one form to another. In this case, the potential energy of the weights is being converted into rotational kinetic energy.