A boy holds the rope so it can't move. What is the tension in point A?
The Attempt at a Solution
The answer in the book is 4N. I understand how to get it, but, I believe that the tension of S1 would be 9N (due to m1), and then the forces on m2 would be gravity, TA and TS1. Together, we don't get zero, but 3N. Is there a problem or am I wrong?