# solve angular speed based on moment of inertia

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An ice skater has a moment of inertia of 5.0 kg-m^2 when her arms are outstretched. At this time, she is spinning at 3.0 revolutions per second. If she pulls her arms in, she decreases her moment of inertia to 2.0 kg-m^2. How fast is she spinning then?

Please provide detailed explanation.

https://brainmass.com/physics/angular-momentum/solve-angular-speed-based-moment-inertia-462817

## SOLUTION This solution is **FREE** courtesy of BrainMass!

In this question, there is a conservation of angular momentum.

Angular momentum = (Moment of Inertia) x (Angular Speed)

The initial angular momentum must be equal to the final angular momentum.

(Mom. of I.)1 x (Ang. Speed)1 = (Mom. of I.)2 x (Ang. Speed)2

5 kg.m^2 * 3 rps=2 kg.m^2 * w

Therefore the angular speed of the ice skater (w) = 5x3/2 = 7.5 rps.

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