A skater spins with an angular speed of 12.4 rad/s with her arms outstretched. She lowers her arms, decreasing her moment of inertia by a factor of 8.00. Ignoring friction on the skates, what will be the skater's final angular speed?

3 answers

I wonder what makes this a "world" problem. The same laws of pysics apply to the nationals and regional competitions, as well as practice sessions. Do you mean a WORD problem?

When friction can be ignored, which is nearly true in figure skating if you are skating on your edge properly, then angular momentum is conserved (wh8ich means it remains the same) during spins. The angular momentum is the product of the moment of inertia and the spin rate, in radians per second.

If the skater's moment of inertia decreases by a factor of eight (which is very hard to do, but possible), then the spin rate must increase by the same factor in order to keep the angular momentum the same.

So, multiply 12.4 by 8 for the answer, in radians per second.

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