Day 6: Speed Dating in CVPM


We did physics speed dating (see this blog post by Kelly O'Shea if you want to know more) to tackle the most complicated constant velocity representations we'll do. I have to be careful at this time of the year; I can spend a lot of time making sure their model of constant velocity is perfect, but I don't think it really matters for a few reasons:
  • We will get a chance (literally in the next unit) to deepen our understanding of these representations.
  • It takes a lot of effort to get the last bit of refining. Do I care what they do on motion maps with the last dot? Well, no, not really. If a student decides to draw the position-time graph one more second to what the arrow says will happen next, I'm OK with that. I'm sure other physics teachers have strong opinions about this, but I don't, and more importantly...
  • I don't know what we'd get out of having the best constant velocity model. Constant velocity isn't the cornerstone of physics. The next model is. I don't care if there's a small mismatch between my model of constant velocity and theirs. 

Still, even with this leeway, we still have some important discussions:

  • Where does a position-time graph? Does it always start on the vertical axis? Does it always start with the first dot?
  • What happens between one region of constant velocity and another region? How can the velocity change and no time pass?
  • What do the numbers on the motion map diagram represent?