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

so a student is sitting on a spinning stool and has a 2kg dumbbell in each hand angular velocity is 3rad/sec arms stretched out is a radius of 80cm and he pulls in his arms to 20cm. for this problem your ignoring the students weight.

from other problems i have figured out

so angular velocity to start with is 3 rad/sec

angular velocity final is 48 rad/sec

kinetic energy initial is 11.52( dont know what this dimensions is so im guessing J)

kinetic energy final is 184.32

angular momentum = 7.68

and i need to find the force required to pull one of the dumbbells in at a constant speed is equal to F=((initial angular momentum of 1 block)^2)/(4*Mass of one weight*Radius^3))

2. Relevant equations

I=[tex]\sum[/tex]mr^2

k=1/2I[tex]\omega[/tex]^2

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

L=I[tex]\omega[/tex]

3. The attempt at a solution

do i say Torque=F*d and Torque=I*alpha and then go Force = Ia/d? or is there another way to solve this that im not seeing ?

or do i use the change in kinetic energy equation 1/2*I*[tex]\omega[/tex]^2Final-1/2*I*[tex]\omega[/tex]^2initial = F*d

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# Force in relation to angular momentum

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