1. The problem statement, all variables and given/known data A 1.0 kg mass and a 4.0 kg mass are attached to a lightweight cord that passes over a frictionless pulley. The hanging masses are free to move. What is the acceleration of the larger mass? What is the tension on the cord? 2. Relevant equations F(net force)=F(tension)-weight F=ma 3. The attempt at a solution I found the acceleration using F=ma. The system has 3 kg of mass going down (4kg-1kg), which is equal to 29.4N of force (found by multiplying 3kg by 9.8m/s^2). The whole system has a mass of 5 kg, so I substituted in to F=ma. 29.4N=5.0 kg + a The acceleration is 5.88 m/s^2 Now comes the part I am confused about. The tension of the cord should be F(net force)=tension-weight, or rearranged to be: F(tension)=F(net force)+weight or (Tension=ma+mg) I can substitute in what i know: Tension =m(5.88m/s^2)+m(9.8m/s^2) I am at a loss of which mass to use. Do i use the mass that i found in working on acceleration (3 kg), or the mass of the whole system (5 kg)?