# Day 59: Standing Waves and Zombies

Tuesday, Dec 4

Physics: Stars and Black Holes. Still on cosmology. This curriculum is so disjointed and contextless, and the students don’t really know or understand what’s going on. I can’t fix it without going way outside the realm of what the other classes do and causing even more problems in the long run. So, we watch the same videos, and I try to help them interpret and understand, and the days move on.

Honors Physics: Standing Waves! I did things a big differently this year. I used the “wave on a string” flash app where you wiggle the wrench and can have open or closed endings (similar to this PhET sim, but not the same) and showed them some reflecting pulses, then showed them a reflecting full traveling wave and we watched it turn into a standing wave as it reflected and interfered. I’ve seen the sim dozens of times, but this was the first time I thought to use it like that, show it repeatedly, and as have them look and notice different things each time we watched it. Then when I made standing waves in real life, they were much more receptive to the idea of how they are made and how they are related to traveling waves. I want to talk a bit more about reflecting pulses and when strings of different masses are attached to one another, but we’re right on track to begin the math of standing waves and stringed instruments. I am excite.

AP Physics: Zombie Apocalypse Lab!

We’ve got two rotational inertia rods. One has all the mass at the center, and the other has that same amount of mass with half at each end. The job of the students is to make a coherent argument regarding which one would be a better weapon during a zombie apocalypse and why using ideas of physics. They’re supposed to talk about rotational inertia/acceleration/momentum/energy in their argument. They can look at it from any angle, whether from being easier to swing, faster recovery time, does more damage, does more damage in a given time, whatever they think is the most important aspect of zombie defense. This year they are taking it SUPER seriously, and I have to keep talking them out of the weeds of calculating the exact torque on the rod through a 90 degree swing starting from vertical and other such things. That’s far beyond the scope of what is necessary. Make some assumptions about what is the same and what is different, then explain how the differences matter using ratios for the concepts.

When I did this last year, it was some of the best lab reports I’ve ever read.