A student sitting on a frictionless rotating stool has rotational inertia 0.88 k

Question

A student sitting on a frictionless rotating stool has rotational inertia 0.88 kg*m^2 about a vertical axis through her center of mass when her arms are tight to her chest. The stool rotates at 7.00 rad/s and has negligible mass. The student extends her arms until her hands, each holding a 5.5 kg mass, are 0.73 m from the rotation axis. A) Ignoring her arm mass, what's her new rotational velocity? B) Repeat if each arm is modeled as a 0.73 m long uniform rod of mass of 4.6 kg and her total body mass is 57 kg . (in rad/s) I got .30rad/s but he keeps saying that is the wrong answer...please help!!!!

Explanation / Answer

(A)

angular momentum is conserved.
=>Iii = Iff.

Ii = 0.88 kg*m^2

i = 7.00 rad/s

If = Ii + 2mr^2 = 6.74 kg*m^2.

=>f = Iii/If = 0.913 rad/s.

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