# Day 35: The Conical Pendulum and Acceleration Toward the Center

Monday, Oct 23

Physics: Exam! I chopped it down to 10 MC and four free response instead of 12 and 5, because I ask them to do more writing and showing work than my colleague, so they need more time to do fewer problems. The terrible part was all the typos in the exam. I hate when I flub things to quite that extent. I was able to write corrections on the board, but I know that kind of confusion is unhelpful. Ah, well. The kids generally did well.

Honors Physics: Conical Pendulum! We learned about the acceleration that makes stuff turn and points toward the center. The word “centripetal” never came out of my mouth, and we only talked about it in terms of the acceleration and never the force, because holy smokes does that make things more confusing for the students. A force is just a thing that happens when objects interact. Centripetal is a direction, not an interaction. Sure, the acceleration is parallel to the net force, which is pointing to the center, but never calling it a centripetal force means students don’t think it’s some kind of new thing they have to do different things with and sometimes even put the damn thing on a FBD. If you don’t even mention it, that doesn’t happen, and there’s no weirdness about centripetal vs centrifugal or whatever. It’s just the acceleration towards the center of a circle and happens when you have a net force perpendicular to the motion.

AP Physics: First class did more measurements to try to determine the relationship between period and length. It did not go quite as well as I wanted. The two kids who are super into problem solving and figuring stuff out went all in and the other students just sat there, and nothing I tried managed to redistribute the work more reasonably. I am going to have to seriously re-think that activity and develop more engagement. Second class did the class-wide testing of mass/angle/length. They were a lot more engaged and involved in it.