In this clip, students are gathered around in a whiteboard circle for a discussion regarding the forces acting on a person climbing a rope with a set of tools. One student explains how their group considered the tools and the person as one system, and since they’re sitting still, the force of gravity acting on them has to equal the force of the rope. Another group points out that if the tools were removed, then the climber’s force would be greater than gravity, and they would no longer be still. Therefore, they claimed, the tools had to be accounted for separately, and that the combined forces of gravity on the tools and the climber equaled the force on the rope.
This clip takes place during week 9 (Investigating Forces Part 2). The problem being discussed is number 3 from the “Newton’s second law variations on a theme” activity worksheet.