In this clip, the professor is addressing the class as they sit at their desks. The discussion focuses on the energy pie charts of a cup of coffee on a table. The professor and the class come to the conclusion that in order to show a change in energy, more than one energy pie chart is needed. They also come to the conclusion that two energy pie charts are needed to show that there is no change in energy—by keeping the pie charts the same size and with the same constituents. Also, since the coffee cup is on a table, they come to the conclusion that it has gravitational energy. At the end of the clip, the professor states that they need something new—Forces.
This clip takes place in week 8 (Investigating Forces). The discussion is based off of an activity that asked the students to create a complete model for a coffee cup sitting on a table. The goal of this activity was to motivate a shift to forces.