1. The problem statement, all variables and given/known data The diagram shows a system of two blocks suspended by ideal strings and pulleys. If the tension of the string attached to block m1 is T, what is the tension of the string attached to block m2? 2. Relevant equations Due to conservation of string, a1/2 = a2 Force balance on mass 1: ∑F1 = m1a1 = m1g - T Force balance on mass 2: ∑F2 = m2a2 = m2g - T2 3. The attempt at a solution Substituting a1/2 = a2 into the ∑F2 expression, I get a1 = 2g - 2T2/m2 Substituting the above into the ∑F1 expression, I get T2 = m2g/2 + m2T/(2m1) The correct answer is given as 2T. I'm struggling with this, because I don't see how the pulley could accelerate upwards if this is true, as all forces are balanced.