In this clip, a small group of students are working on a problem at their desks and call the professor over for assistance. One student asks the professor if vectors can be moved around. The professor explains that they should look at the forces, and suggests drawing a force diagram. The students conclude that the net force is equal to the force of friction plus the force of the spring.
This clip takes place during week 13 (Investigating Spring Forces & Circular Motion). The students are working on problems from the “Investigating Spring Forces” lab.