# Homework Help: Atwood machine with two holes in pulley.

1. Jul 11, 2012

### AbigailM

1. The problem statement, all variables and given/known data
A system consists of a pulley and two masses m1, m2 haning from it as shown in the figure. The pulley is a disk of radius R with constant mass density that has two circular hole with radius R/2. Find the angular acceleration of the pulley.

Figure attached.

2. Relevant equations
L=T-U
$I=I_{cm}+mh^{2}$

3. The attempt at a solution
The solution is attached.

I'm not interested in knowing if my calculation for the moment of inertia is correct which is found at the bottom of the solution.

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• ###### F10-5sol.jpg
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2. Jul 12, 2012

### TSny

In the first equation for I at the bottom of the page, shouldn't the last term be negative? (Never mind, I missed seeing a set of parentheses!)

It all looks good to me.

3. Jul 12, 2012

### AbigailM

Ooops I made a typo. I meant to say that I'm interested in knowing whether or not my moment of inertia is correct.

Oh cool TSny you read it how I meant it.