Skater begins to spend with arms held out at shoulder height. The skater wants to match the speed of the spin to the beat of the music. How does the skater use knowledge of the conservation of momentum to do this?

this allows people to make the best decision or pursue the best option. when alternatives are weighed using their advantages and disadvantages, the option whose disadvantages outweigh the advantages (based on a qualitative or quantitative analysis) are shunned while those whose advantages outweigh their disadvantages are pursued.  

thermal energy is the answer

what is the actual question though?