Last week a couple of my students were dressed up for something, and I remarked how good they looked and that we should do a Phormal Physics Phryday; they latched on to it. I also mentioned it to my colleague Ben, whom I work closely with, and many of his kids did it as well. Above is the collection of students we could get together after school, and below is most of my 3rd period class, the originators of the idea.
Today we started unbalanced forces by brainstorming situations where we could explore how unbalanced forces operate in the lab. On kid actually described an Atwood Machine perfectly without using the name, so I drew it and commented on how it is a famous physics apparatus. We will be pulling something with a spring, thought I am fine with groups choosing other options as well if they want. This particular lab, as a paradigm for UBFPM, I want to keep them uniform. We’ll be doing some more open lab design to investigate friction later.
Recently I find that every time I say something like “the best way to approach this problem is…”, kids find a clever, elegant, or just different way to approach it. The force addition diagrams above are a great example.
The kids had some pretty awesome problem solving going on today.
I’ve probably written about this before, but Kelly sold me on force addition diagrams last year and I don’t think I’ll ever look back. So far I haven’t come across a situation that I’d rather use components on. This was from the problem below, we spent a whole hour on it. At this point this group was still wrestling with how to use the FAD to solve the problem.
This graph is created from the setup shown below, a modified Atwood machine, showing that the tension in the rope decreases when the system starts to accelerate. I’m going to spend a day having students predict, then whiteboard with diagrams, then replicate the situation with data.
My students are struggling on the difference between equal and balanced. This is what I wrote on the board, but not sure I like it. Thoughts?