This week, we worked on developing the concepts of momentum and center of mass. We wrapped up a video analysis exercise (based on an article in The Physics Teacher by Taylor Kaar, Linda Pollack, Michael Lerner, and Robert Engles) where students track a system of two air pucks attached by a rod. Students made a lot of nice connections between the observed motion and Newton’s Laws, which lead to a lot of great discussion about what objects to include in a system to make sense of the motion. I also got to feel very cool demonstrating center of mass in an explosion with a track balanced on some blocks.

Physics: Vector Addition Diagrams

Students worked on solving problems with vector addition diagrams for balanced forces. We started with an activity I got from Casey Rutherford where students use pipe cleaners to rearrange the vectors on a free-body diagram before moving into problems on paper. A lot of my students struggle with the idea of rearranging the FBD, so starting by literally rearranging the vectors tends to be a useful stepping stone.