Days 64-67: Kinetic Energy & Newton’s 2nd Law

This week was a little goofy. Tuesday was our first day back from break, then a big winter storm meant we had to close schools on Wednesday. We used up our regular snowdays in December, so Wednesday was an emergency e-learning day, which means students completed asynchronous assignments.

AP Physics 1: Kinetic Energy

Our first task back from break was to find the relationship between velocity and kinetic energy. I waffle every year whether to do this with tracks and probeware, which as the advantage of being firmly rooted in the real world for students, or use Pivot Interactives, which has the advantage of measurements that are easier to make. With the weather forecast, I opted for Pivot. I had students complete the first section that takes them through making measurements and modeling the energy transfers with energy bar charts individually, then complete the remaining sections in groups. It’s been a little while since we linearized a graph or developed a mathematical model from data, but I was really pleased with how they did.

Physics: Newton’s 2nd Law

Our big goal this week as a paradigm lab for Newton’s 2nd Law. In some conversations last year, Kelly O’Shea suggested using carts on ramps as an alternative to the more standard modified Atwoods machine. Students used a force sensor to measure how much force it took to hold the cart in place. Next, we used some vector addition diagrams to reason out the force they’d measured is the same as the net force when the cart is released. Students used the motion encoder carts to determine the acceleration, then changed the angle of the ramp and repeated their measurements. I really like that this is conceptually much simpler than the modified Atwood, so students can focus on making sense of the data, and this approach makes a really clear conceptual link between balanced forces and unbalanced forces. For the e-learning day, we had students do some reasoning with vector addition diagrams of balanced forces to help review those skills to support the lab.

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