This has been frustrating me: Problem: The pulley in the figure is essentially weightless and frictionless. Suppose someone holds on to m=10.0 kg and accelerates it upward at 4.905 m/s/s. What will then be the tension in the rope given that M=10.0 kg? Attempt: The sum of the forces on m = Ftension + Fhand - Fgravity = ma The sum of the forces on M = Ftension - Fgravity = Ma I said Fhand= m * upward acceleration I tried solving for 'a' on both equations, then set them equal to eachother to solve for Ftension. This gave me a ridiculous answer, and I'm pretty sure I didn't screw up my math. I must have set it up wrong? Please help!