# Day 86: a vs v or v^2?

Today we started by plotting a vs. v from the spinny chair experiment.  For most groups the data either looked non-linear or they had crazy negative intercepts. I took time to go to each group to ask questions about those aspects, and guided them toward linearizing their graph as a result, since it’s been a long time since we last linearized and we only did it once. The data ended up great after linearizing by squaring v, and it became clear to the students through the discussion that the slope was smaller for groups with higher radii. That plus a unit analysis of the slope led to the conclusion that $a=\frac{v^2}{r}$. A couple other graphs below.