Dear all, I hope you could help me out a little. 1. The problem statement, all variables and given/known data A person tries to raise a chain of 3 identical links; where each of the links has mass m. The chain is connected to a string is suspended vertically with the person holding the upper end of the string and pulling upward. Because of the person´s pull an upward force of F is applied to the chain by the string. a) Find the acceleration of the chain. b) Find the force exerted by the top link on the middle link. 2. Relevant equations F = m*a 3. The attempt at a solution I was able to get the acceleration which is (F-3mg)/3m! For part B i was able to get the answer: 2(mg+ma). Which i believe is correct. But the program i am using tells me the answer is wrong and doesnt depend on the variables m and a. Is there another way to describe this? Please help.