Today we finally were able to have the post-lab discussion on the collisions experiment. It was a bit of a different style of discussion. I had each group prep a WB with a description of each collision it studied, they demonstrated each one and we viewed the movie the group posted. I also had the group provide the initial and final momenta values for each collision, then we looked at the pooled data from all of the classes for that type of collision. For the most part our results were pretty decent. We had wanted a slope of 1.0 to establish the conservation of momentum. The inelastic collisions were the most accurate. I think this is because there is only 1 ‘thing’ (the connected) carts to determine the velocity for. Next year I think I need re-enforce the concept that we really need the instantaneous velocity right where the carts collide. I had a few groups put on a linear fit so the velocity was a bit off. Tomorrow we will compare the total initial kinetic energy and total final kinetic energy. As the homework for tonight, each group needed to simply add a column or three to the spreadsheet so the kinetic energies could be calculated.
Today we had the WB discussion on the Hooke;’s Law experiment with the springs. For some reason, this time around, quite a few groups had significant intercepts… I even had a few groups re-gather the data with the same results. Interesting enough, the slope values were pretty much spot on with the given values. Tomorrow, we are planning to practice with the spring constant concept by asking a few ranking task and quantitative questions.