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

Consider a hollow tube of mass M = 1.2 kg and length L = 1.6 m that rotates about an axle through its center and perpendicular to its length. Inside the tube are two masses, m_1 = 0.4 kg each. These masses are initially held a distance d = 0.8 m apart by a string and centered in tube. The maximum tension the string can sustain is 100 N. You may consider that the radius of the tube is negligible (i.e. its moment of inertia is that of a 'stick') and that the masses held by the string are point-like.

1.1 Starting from rest, the cylinder starts to rotate as a result of a constant driving torque applied to it. What is the work done by this torque up to the point at which the string breaks?

2. Relevant equations

Work=[tex]\tau[/tex][tex]\theta[/tex]

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

F=ma=m[tex]\frac{v^{2}}{r}[/tex]=m[tex]\omega[/tex][tex]^{2}[/tex]r

3. The attempt at a solution

Wow I'm really lost with this one. Here's what I tried.

I=.5MR^2+2mr^2

F=m[tex]\omega[/tex][tex]^{2}[/tex]r

100=2(.4)[tex]\omega[/tex][tex]^{2}[/tex](.4)

[tex]\omega[/tex]=17.667

F=m[tex]\alpha[/tex]R

100=2(.4)[tex]\alpha[/tex](.4)

[tex]\alpha[/tex]=312.5

Definitely feel like I'm doing something wrong here.^^^

So with that I could find the torque using torque=I*alpha, but I would still need to somehow find the angle theta. I'm pretty sure I'm approaching this problem wrong.

Any help is appreciated!! Thank you. Sorry about the formatting, I'm not sure how to put the symbols in correctly.

The symbols appear to be in superscript but they should not be.

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# Homework Help: Torque, angular momentum, moment of inertia

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