Question

A figure skater is spinning at a rate of 1.7 rev/s with her arms outstretched. She then draws her arms in to her chest, reducing her rotational inertia to 64% of its original value. What is her new rate of rotation?

Answer 1

Use conservation of angular momentum

L1*W1 = L2*W2

We're solving for W2

From the information given in the question:

L2 = 64*(L1/100) = .64*L1

W2 = (L1*W1)/L2

So plugging this into the momentum equation:

W2 = (L1*1.7)/(.64*L1)

We can kill the L1 on top and bottom leaving us with:

W2 = 1.7/.64

W2 = ___ rev/s