A student on a piano stool rotates freely with an angular speed of 3.33 rev/s. The student holds a 1.44 kg mass in each outstretched arm, 0.759 m from the axis of rotation. The combined moment of inertia of the student and the stool, ignoring the two masses, is 4.34 kgm2, a value that remains constant.(adsbygoogle = window.adsbygoogle || []).push({});

(a) As the student pulls his arms inward, his angular speed increases to 3.54 rev/s. How far are the masses from the axis of rotation at this time, considering the masses to be points?

(b) Calculate the initial and final kinetic energy of the system.

For the first part, I tried doing mr^2w(initial)=mr^2w(final) and it said that my answer was within 10% of the correct answer. I tried doing different variations, playing around with the given moment of inertia, but I couldn't figure out how to factor it in along with the varying radius.

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# Homework Help: Conservation of angular momentum on a piano stool

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