1. The problem statement, all variables and given/known data Two monkeys of masses 10kg and 8kg are moving along a vertical rope (There's just a single vertical rope in the diagram, attached to a fixed support (no Atwood's machine kind of thing), with two monkeys drawn on it.) The first monkey (this monkey is above the other monkey, but obviously below the fixed support), is climbing up with an acceleration of 2m/s^2, while the second monkey is coming down with a uniform velocity of 2m/s. Find the tension in the rope at the fixed support. 2. Relevant equations 3. The attempt at a solution So, basically, the solution says that you add the tensions due to both the monkeys, ie T1-100=20 (from first monkey) T2=80 (Second monkey) Adding T1 and T2, you get 200 N. How can the tensions possibly be different in a mass-less string at different points? And why are we adding both the tensions to get the tension at the fixed support?