1. The problem statement, all variables and given/known data A cord passing over a frictionless, massless pulley has a 4.0 kg object tied to one end and a 12 kg object tied to the other. Compute the tension and acceleration in the cord. Right now, I'm just trying to calculate the acceleration. It is supposed to be 4.9 m/s^2 2. Relevant equations F=ma T1=T2=0 T1-mg=ma T2-mg=ma 3. The attempt at a solution For the 4kg block- F=ma T1-mg = ma T1-39.2 = 4a Solving in terms of T1 to get T1= 4a+39.2 For the 12kg block- F=ma T2-mg = ma T2-117.6= 12a Solving in terms of T2- T2= 12a+ 117.6 Now, because T1=T2, I can say 12a+ 117.6 = 4a+ 39.2 But then I end up with a=9.8. The answer is 4.9, which, incidentally, is 9.8/2. Do I have to divide by 2 because I have two cords? Or is there some other reason I am missing?