## Day 7: What does the P mean in CVPM?

We took our first quiz today about CVPM. But our short lesson today was about the particle in constant velocity particle model.

Mr. Kaar, Mr. Engels, and Ms. Pollack, and I created a unit to explore what "particle" means in CVPM, and how it relates to conservations of quantities in systems. This lesson is the first part of this.

We start with a video of two air pucks connected by balsa wood sliding along the ground. We make sure we know what those air pucks are, and how they seem to move at CVPM. We then learn how to track one air puck. (See awesome gif above. Thanks, gifmaker.me!) Cool, a motion map! That motion map doesn't look like CVPM at all! We look at the position-time graph, and that doesn't look right either. It's way more complicated than a straight line. What should we track? Students usually quickly realize the middle is what we should track. We then do the same thing for three air pucks attached into an equilateral triangle. What should you track now? That's more difficult, because the middle isn't really part of anything. But it still works!

We then give them the two pucks again but this time, when they track the center, it doesn't look right. Why? Because we secretly filmed it on the ramp outside. So that's why the dots on that motion map aren't equally spaced. It seems to be speeding up, which is what we'd expect on a ramp. Guess we'll have to test things on ramps with the motion detectors on Monday...