In this clip, a group of students are engaged in a discussion with the professor at their desks. They are discussing a system involving two masses, a rope, and a pulley. The discussion is regarding how far one mass will move, if the other is moved a certain amount. The professor leads the students to the conclusion that they are making the assumption that the rope doesn’t stretch.
This clip takes place during week 6 (Becoming Quantitative with Energy). The problem that the students are working on is problem #2 from the “Energy Problems for Practice” worksheet.