Today we started whiteboarding the first set of problems for the central force particle model unit. I’ve been very careful to focus on the net force applied to an object undergoing uniform circular motion and focus on the forces that result in an unbalanced force directed toward the center of the circle. Despite this, one group will present this whiteboard tomorrow:
They have added an additional force “Fc” to their free-body diagrams. It is interesting that this has appeared despite me never having used the abbreviation Fc. Regardless, it will result in a good discussion tomorrow.
Students started to finish their media computation collages today. The rest will be submitted throughout the weekend. I love the creativity and individuality that this lab provides. Great start to the semester before tackling ArrayList next week.
In AP Physics B, we spend a lot of time learning to visualize electric fields and equipotentials. One of the most helpful activities to develop this visualization is a lab where students map the electric potential on a grid of conductive paper and enter the results in an Excel spreadsheet that generates a 2D contour plot and a 3D surface plot. (This is the one time during the year we use Excel.) The 3D surface plot is particularly good at helping students visualize the electric field and equipotentials. We use a modified version of the spreadsheet that comes with the Advanced Physics with Vernier – Beyond Mechanics Lab Book
I believe this surface plot is of two concentric circles (high potential is the inner circle).
Today we started the Central Force Particle Model with a conceptual paradigm lab. I have never tried bowling balls and mallets before, but I picked up some cheap mallets over the winter break and found four bowling balls that we had laying around. The activity was a good review of unbalanced forces. It was reassuring to see students converge on the concept that a force directed toward the center of a circle is required to keep the bowling ball moving in a circle. We worked in the hallway instead of on a basketball court. We’re not suppose to put tape on the waxed floors; so, we used a hula hoop as the indicator for the circle. The lab went well, and I’ll need to find a couple more bowling balls for next year!
Tonight we welcomed 8th graders. The Career and Technical Education department does a great job promoting the options available to students. My colleague, @Mr_Alesch and I promoted the computer science classes that we offer and answered a lot of questions from parents and students. The code.org materials make it easy to have professional materials and videos to help in recruiting. We also showed the video I created to highlight computer science and student projects.
The lab practical for the Momentum Transfer and Energy Transfer Models unit was to determine the velocity of a projectile using a ballistic pendulum. It’s a classic application of momentum and energy. In hindsight, I realized that I should have had groups compare the velocity determined based on the ballistic pendulum with that determine last semester using other methods. Next year!
I like that we came back from an extended break and started the Momentum Transfer and Energy Transfer Models unit. It gives students time to get back in the swing of things by applying familiar models. Great whiteboards today including a mistake that lead to a great discussion. This whiteboard was my favorite (despite the IFF chart).