Day 141: Center of Mass & Epicenters

AP Physics: Center of Mass

I started class a center of mass demo that I think I first saw from Dan Burns. I balanced a dynamics track on a block and placed a couple of carts in the center, then asked students to predict what should happen when the carts launched. Afterward, students prepared whiteboards with their solutions for the free-response problems we’ve been working on this week.


Earth Science: Epicenter

Students used some simulated seismographs and a travel time curve to locate the epicenter of an earthquake. A lot of students struggled with reading the travel time curve, so I need to do a better job of scaffolding it next time. The seismographs had time marked with the number of minutes after an arbitrary zero, which made it difficult for students to separate the arrival time of the waves from the actual travel time; next time, it would be better to use seismographs with actual timestamps. I also would like to have students spend some time interpreting the travel time curve before trying to combine it with seismograph data.


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