Atwood machine, solve for angular acceleration

[aznboi855]

Homework Statement

The goal is to solve for angular acceleration with the end variables being m1,m2,m3, R, r, g.
M2 > M1.
An atwood machine is a pulley with 2 masses, one on each side.

Homework Equations

Tnet = I * angular acceleration
Fnet = ma

The Attempt at a Solution

I know you have to solve for both the masses and the pulley itself, but how do you relate them?

 

[Doc Al]

How does the angular acceleration of the pulley relate to the linear acceleration of the masses?

 

[aznboi855]

It's the same?

 

[Doc Al]

It's the same?

How can an angular acceleration be the same as a linear acceleration? (But they are simply related though.)

 

[aznboi855]

I must've misunderstood your question, I simply thought that because the mass is having a linear acceleration downward, therefore causing the pulley to have an angular acceleration, they must be the same :S. I'm bad at this angular stuff :(.
Angular acceleration the change in angular velocity over time, and angular velocity is the change in angle over time... so... I still can't relate them :S.

 

[Doc Al]

Hint: Given the angular acceleration of the pulley, what's the tangential acceleration along its circumference?