Can you identify the relevant physical principles and summarize them in words?

Problem: There are two blocks, one on top of the other, that are connected by an ideal massless rope and pulley.The lower block in the figure is pulled on by another rope with a tension force of 26 N. The top block hasa mass of 1.4 kg and the bottom block has a mass of 3.0 kg. The coefficient of kinetic friction betweenall surfaces is 0.22 and the coefficient of static friction between all surfaces is 0.34. a) What is the acceleration of the lower block? b) If a third mass was stacked on top, what minimum mass would be required so that the system doesnot move?