- #1

awelex

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## Homework Statement

See picture: http://session.masteringphysics.com/problemAsset/1038667/6/YF-05-85.jpg

All pulleys are weight- and frictionless, as are the ropes.

Find the acceleration of block m3, of pulley B, of block m1 and m2, the tension in String A, and the tension in string C.

## Homework Equations

## The Attempt at a Solution

To find the acceleration of m3, I thought of m1 and m2 as a single mass, which should turn the problem into a simple Atwood problem. The two equations that I got out of this are:

(m1+m2)g - T2 = (m1+m2)*a

T2 - m3*g = m3*a

Solving for a yields g*(m1 + m2 - m3)/(m1 + m2 + 2m3), which is not even close to the solution.

What am I doing wrong?