(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 120g Frisbee is 28cm in diameter and has about half its mass spread uniformly in a disk, and the other half concentrated in the rim. With a quarter-turn flick of the wrist, a student sets the Frisbee rotating at 560rpm.

(a) What is the rotational inertia of the Frisbee?

(b) What is the magnitude of the torque, assumed constant, that the student applies?

2. Relevant equations

I=1/2*m*r^{2}

I=m*r^{2}

[tex]\tau=I\alpha[/tex]

3. The attempt at a solution

I got the first part of this by using I=1/2*.60kg*.14m^{2}for the disk then adding I=.60kg*.14m^{2}for the rim which gives me 0.001764kg/m^{2}

The part that is messing me up is finding the torque, I think the best way to find the torque is to find the angular acceleration of the frisbee, but I havn't been able to get it. I am pretty sure I need to use the rotational/kinematic equations... Any help would be great.

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# Rotational inertia and torque

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