Conservation of Angular Momentum in Skater's Spin Rate Change

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A figure skater initially spins at 2 rev/s with her arms outstretched and reduces her rotational inertia to 61% of its original value. The conservation of angular momentum principle states that the angular momentum before and after the change must be equal. To find the new rate of rotation, the correct formula involves setting the initial angular momentum equal to the final angular momentum and solving for the new spin rate. The attempted solution of w = 2.56 rev/s is incorrect, indicating a need for a proper equation setup. Understanding and applying the conservation of angular momentum is crucial for solving the problem accurately.
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Homework Statement



A figure skater is spinning at a rate of 2 rev/s with her arms outstretched. She then draws her arms into her chest, reducing her rotational inertia to 61% of its original value. What is her new rate of rotation?



Homework Equations



?



The Attempt at a Solution



w/2 = 1/sqrt(0.61)
w = 2.56 rev/s

This isn't correct according to the website, can someobody help me with a better equation and how to solve this one?

Thanks!
 
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angular momentum before = angular momentum after
 
I still don't really understand
 
Angular momentum is conserved; it stays the same unless there is an external torque. So
angular momentum before = angular momentum after

You need to write the formula for angular momentum on both sides. Fill in the quantities you know and solve for the one you want to find.
 

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