1. The problem statement, all variables and given/known data I am currently taking a Summer physics course, and today we were given a Force/Friction problem that even after the professor explained, I could not fully understand. https://de6d4c993829dd9a7ebe8c71bf32cb36b6fe5892.googledrive.com/host/0B79Pxd57IVb7aWU0Q3JqeG5XbjQ/FreeBodyFrictionPrblm.png [Broken] Mass of Objects: m1=5.0kg m2=2.0kg Given Friction Valules: Mk1 (Between Block and Surface) = 0.20 Mk Mk2 (Between Blocks) = 0.15 I am supposed to find acceleration, as well as the tension between the two masses. 2. Relevant equations Equations that he used to solve the problem: n-mg=0 Force-Kinetic Friction-Tension = mass*acceleration 3. The attempt at a solution I was able to draw a free body diagram of the system, however, I only included 2 values for normal force and Kinetic Friction, where in his complete Free Body Diagram, there were 3 values for both. I really got lost when he solved the problem using a system of equations towards the end. The acceleration ended up being 80/7 m/s2, or about 11.4 m/s2, and tension ended up being around 26 N. I have been studying this topic, but I don't really understand the fundamentals of the whole process, and memorizing formulas hasn't helped whatsoever. Any guidance would be greatly appreciated!