# Day 20: Force Diagrams, v-t Graphs, & Diffusion

AP Physics: Force Diagrams

We went over the force problems from last week. I skipped having them whiteboard all of the trig and algebra, and just had students whiteboard the diagrams and some selected reasoning. There was some good debate on whether the normal force should equal gravity on some of the problems, and the vector addition diagrams were a great tool for reasoning that through.

Physics: v-t Graphs

Students whiteboarded their solutions to Friday’s constant velocity problems. The problems were a lot more challenging than I expected. One big struggle for a lot of groups was making sense of what the problem was asking. The other big struggle was connecting strategies and ideas from one problem to the next one. For example, after using the area of a velocity vs. time graph to find displacement on the first problem, many students struggled to find the displacement from a v-t graph on the second problem. This tells me students were following a procedure without understanding why, so I need to think about how to step back and get that idea across.

Chemistry Essentials: Diffusion

Students whiteboarded particle diagrams for perfume dispersing through the classroom and food coloring dispersing through water. In both cases, students made a lot of great observations prior to whiteboarding and had a lot of good foundation on their whiteboards.