Spinning Skater

Classical Mechanics Level 2

An ice skater is standing with his arms wide, spinning on the tip of one skate. By pulling his arms in, his moment of inertia is reduced to 60% of its original value.

If \(K\) is the original rotational kinetic energy of the skater and \(W\) is the work done in pulling in his arms, what is the ratio \(W:K\)?

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