Day 82: Board Meeting & Experimental Error

AP Physics: Board Meeting

Students whiteboarded their results from the cart explosion lab to start building the momentum transfer model. I can tell its been a while since we’ve done a true model-building lab, so students needed some reminders about how to linearize or “translate” y=mx+b, but those skills came back pretty quickly. I did wish I’d had students linearize a bigger variety of graphs so far this year; a lot of students went straight to squaring a variable, so I may want to think about how to get more variety early in the year next year.

When we discussed the lab, a few groups had linerized based on a quadratic relationship and had a fairly large intercept. To decide whether the large intercept made sense, one student suggested exploding the plunger cart off empty space to get a mass ratio of zero and show the velocity ratio must also be zero.

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Physical Science: Experimental Error

We spent some time discussing yesterday’s speed of sound lab, focusing on error in measurements. I tried having students stand in different parts of the room based on how they thought frequency affects the speed of sound. When students were picking their spots, there was a lot of great conversation, including some contrasting frequency and speed, which was a great side effect. As we talked about error and what it means for values to be “close”, I had a lot of students ask to move because they changed their mind about what the answer should be.

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