# Days 87-91: Pendulums & Conservation of Momentum

AP Physics: Pendulums

This week we started simple harmonic motion. We started by using a video on Pivot Interactives that has a pendulum, a glider on a spring, and a spinning disk that all go through simple harmonic motion with identical periods and amplitudes. Students plotted position vs. time and velocity vs. time graphs. When we shared the results, the students in calculus made some great connections to derivatives. We then moved into a lab to find the factors that affect the period of a pendulum. This is one of the labs where I felt like the hard work learning how to do an experiment really paid off as students worked pretty independently and got great results.

Physics: Conservation of Momentum

This week students worked on practicing conservation of momentum problems. One of their tasks was to figure out an unknown mass using results from a collision. One thing that has been tricky every time we do this practical is students sketch bar charts for what they want the collision will be, such as having both carts come to rest after a collision, but have trouble adjusting if their bar charts don’t match the actual collision. I think this comes down to many aren’t thinking of momentum bar charts as something that describe a physical event. I wonder if it would be helpful to do an activity where students do various collisions between pairs of carts, but focus only on representing those collisions with bar charts.