1. The problem statement, all variables and given/known data In the Atwood's machine below the string passes over a fixed cylinder of mass mc. The cylinder does not rotate. Instead, the string slides on its frictionless surface. (Use any variable or symbol stated above along with the following as necessary: m1, m2, and g. Find the magnitude only.) 2. Relevant equations F = ma 3. The attempt at a solution m1 ƩFY: T-m1g = m1a T = m1(a + g) m2 ƩFY: T - m2g = -m2a Substitute T in m1a + m1g - m2g = -m2a a(m1 + m2) = g(m2 - m1) a = g(m2 - m1) / (m1 + m2) This seems simple enough, but it's not being counted as correct. The acceleration for the center of mass for the system would be the same as the acceleration of the individual blocks, correct?