In this clip, a small group of students are at their desk involved in a discussion with an LA. The discussion is regarding the forces acting on a box. The students agree that gravity is pulling down on the box, and that the normal force is perpendicular to the surface that it’s on. Since the box is at rest, the students know that there has to be a vertical force opposing gravity. After a lengthy discussion involving many non-physics related side-discussions, the students arrive at the conclusion that there is a frictional force opposing gravity.
This clip takes place in week 11 (Investigating Momentum). This discussion is regarding the only problem in the “Box on Wall with Angle” activity worksheet.