On Thursday Physics 10 section 10C had class, and on Friday 10A had class. During the Thursday class, the class went into breakout rooms to whiteboard their responses to questions from the worksheet for the collisions PhET simulation. I switched between the different groups to see if they had any questions, but they understood everything very well, and I mostly answered technical questions about how to use the Jamboard interface, such as how to add a sticky note. The whiteboarding took up the whole class period, and they were unable to start the momentum card sort.

During the Friday class, the students continued the card sort. I switched between the groups, and I was asked several questions relating to the momentum and net force graphs that were a part of the card sort. When answering the questions, I applied what I learned from Wednesday’s classes in regards to thinking about the concept on a basic level. Rather than explain momentum as its own concept, I tried to treat it exclusively as a relationship between mass and velocity. One particular question that came up was why the velocity chart for a given scenario (i.e. the spaceship scenario) opened up and the momentum chart narrowed. In answering this question, I re-explained that momentum was the product of mass and velocity. Both charts effectively show the same thing, since mass is constant between the given objects of a system both initially and finally. In the velocity chart of the spaceship scenario, it shows that when the rocket is fired, the spaceship loses a small amount of velocity and the rocket increases its velocity greatly. The velocity of the rocket is much greater than the spaceship, so it as it is launched it makes the graph “separate”. In the momentum chart, however, it’s representing the product of mass and velocity. Despite its increase in velocity, the rocket is significantly less massive than the ship, so it has less momentum than the ship even after being fired. However, firing the rocket DOES increase the rocket’s momentum and decrease the ship’s momentum, bringing them closer together and making the graph appear to “close”. Admittedly, I had a bit of trouble getting this idea across in a concise way, as with my writing in this post, but eventually they understood and were able to better understand the relationship between the two graphs.

Additionally, there were questions about how to read the momentum charts. To answer that, I once again broke momentum down into the product of velocity and mass, and told them to find the momentum values in the initial setup and the values in the final set up. Those values would represent the flat parts of the charts before and after the change, respectively. This ended up making much more sense to the students I was helping than my answer to the previous question, and after doing the calculations they seemed to understand what was happening in the momentum charts.