The problem statement, all variables and given/known data Three objects with masses m1 = 37.5 kg, m2 = 19.5 kg, and m3 = 11.1 kg are hanging from ropes that are redirected over pulleys. What is the acceleration of m1? Negative numbers for downward, and positive numbers for upward, please. There should be a diagram of what the system looks like attached. The attempt at a solution First I drew a FBD of each of the three masses. I made the tension between mass 2 and 1, the variable T12. I made the tension between mass 1 and 3, the variable T13, just for simplicity sake. So the equations I got from the FBD were: T12=m2a+m2g T13=m3a+m3g m1g-(T12+T13) =m1a Then I plugged in the two tension formulas and simply solved for a, which gave me 0.9939 m/s2. I got the question wrong. What I am really wondering is if it just a wrong sign, and the answer is actually -0.9939 m/s2. Or is there a mistake in the math somewhere that I can not see.