Universal Gravitation

Day 126: Universal Gravitation, Pendulums, & Quiz

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AP Physics: Universal Gravitation

We discussed the results of the universal gravitation lab today. Once we got the inverse-square relationship, students quickly recognized the slope of their graphs seemed to be connected to the stellar mass. Prior to class, students entered their slopes and stellar masses into a spreadsheet, so I projected the data and sorted it to confirm the biggest slopes went with the biggest stellar masses. I also graphed students’ slopes vs. stellar mass to get a pretty good value for G.

chart (1)

Physics: Pendulums

Students whiteboarded some problems from yesterday connecting pendulums to other models we’ve used so far this year, including momentum, forces, and energy. A few students needed some reminders, especially about the direction of tension forces, but were very successful in the end.

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Chemistry Essentials: Quiz

Students took a quiz on molar mass and balancing equations for chemical reactions. Based on a quick glance at their work and input from the para who worked with special education students on the quiz, I think I’m going to see a bi-modal distribution. I’m planning to start stoichiometry, and need to think about how I’m going to support the students who are still struggling with molar mass and balancing reactions when we are starting to use those skills together.

Day 123: Universal Gravitation, Pendulums, & State Testing

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Today, sophomores and juniors are taking state tests, so freshmen and seniors have an off-campus learning day. This is the first time we’ve done something like this and the guidelines were pretty flexible. Both of my physics courses are mostly seniors.

AP Physics: Universal Gravitation

Students finished graphing their data from yesterday’s lab using exoplanet data. I started a thread on Google Classroom for students to post questions to try and encourage some virtual discussion, though it didn’t get any action as students opted to e-mail me, instead. Most of the questions I got related to uncertainty, which is not surprising. There were some great conversations yesterday about uncertainty, including why some measurements had different values for the plus and minus.

Physics: Pendulums

Students worked on graphing and linearizing their data from yesterday’s pendulum lab. I usually give students time in class to linearize their graphs so they talk to me or their group members, but they’ve had enough experience at this point that it shouldn’t be a huge leap to do it independently. A few groups didn’t collect all their data yesterday, so I posted a link to PhET’s pendulum lab so they could still be on track for tomorrow’s board meeting.

pendulum lab

Chemistry Essentials: State Testing

My chemistry students are juniors, so they took the ACT today to meet state testing requirements and were off the hook for the off-campus learning day.

Day 122: Universal Gravitation, Pendulums, & Formula Mass

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Today was our first day back from spring break! We have kind of an odd start to the week since tomorrow freshmen and seniors have an off-campus learning day to accommodate state testing for sophomores and juniors.

AP Physics: Universal Gravitation

Students worked on an activity Lucas Walker presented at AAPT last summer using exoplanet data to find a relationship between centripetal acceleration and orbital radius. I was nervous about having students calculate the orbital velocity and acceleration in a spreadsheet since most of my students don’t have much experience with spreadsheets, but my students were very willing to dive in using the resources I provided and were very successful with the calculations.

Physics: Pendulums

Students collected data to model the impact of weight, drop angle, and mass on the period of a pendulum. I’m continuing to see students much more confident in their physics abilities than even the end of last trimester, and working more independently as a result.

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Using the environment to make measuring release angle easier

Chemistry Essentials: Formula Mass

Students started making sense of formula mass by predicting the mass of various combinations of nuts, bolts, and washers. I wanted to give them something pretty concrete they could test directly in the lab before diving into true stoichiometry. When we shifted to chemical formulas at the end of the hour, a few students got tripped up if they skipped the particle diagram, but the math was pretty obvious to everyone once they got that step.

molar mass lab.jpg

Day 137: Universal Gravitation & Glacier Video

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After no classes yesterday due to state testing, we got back in the swing of things today.

AP Physics: Universal Gravitation

Today continued quick and dirty coverage of some topics on the AP exam that we haven’t really addressed yet. Today, I asked students whether uniform circular motion or free fall is a better description of the Moon’s motion, and students went very quickly to wanting to find the acceleration, so I gave them the Moon’s period and orbital radius, and got out of the way. This served as a nice refresher on circular motion. Once students got a tiny acceleration, we reasoned that a 1/r2 relationship might make sense for gravity and checked that against gravity at Earth’s surface and get to the Law of Universal Gravitation.  Then, since most of my students saw Coulomb’s Law in chemistry, we used the parallels with gravity to make sense of that formula.

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Earth Science: Glacier Video

With conferences tonight, I went ahead and showed the video in the curriculum for today. The video was about the data sources glaciers can provide, which got me thinking about how to have students explore those data sources in the lab. For glacier movement, I’m wondering of something like gak could be used to simulate a glacier, maybe with food coloring drops or toothpick flags to track specific points. For the ice cores, I was thinking it would be really cool to find some scale photos of actual ice cores, especially if I could find a way to have students compare the core data to weather data for that year. Of course I thought of all this while watching the video, rather than last night while I stared at the curriculum materials. Oh well.

Day 45: Central Force Problems & Historical Astronomy

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AP Physics: Central Force Problems

Students worked on a few problems related to central net force causing circular motion. I also introduced Newton’s Law of Universal Gravitation as we discussed a problem about orbits. A couple students got really excited when they realized the connection between Universal Gravitation and Fg = mg; one student decided that called for a dab.

Earth Science: Historical Astronomy

After the quiz on the Moon and planets, I did some short notes on historical astronomy. As part of the effort to incorporate engineering into 9th grade science, the curriculum calls for focusing on the tools astronomers use, but this seems like a great opportunity to incorporate the contributions of diverse groups. Next year, I want to do a better job of balancing the tools with the range of cultures we could talk about. I also want to find ways to make this lesson more active, but need to figure out what I can have students do without making the lesson significantly longer.