My colleague Mark and I are developing a new approach to beginning with energy first, and our second lab of the year is going to be aimed at discovering energy conservation. I’m going to write this up in more detail on my main blog, but the basic idea is that each lab group will be studying a different type of collision:
- dynamics carts with clay bumpers
- dynamics carts with spring bumpers
- dynamics carts with magnetic bumpers
- air track with magnetic bumpers
Students will calculate the total kinetic energy before and after the collision and we’ll look for patterns, hopefully seeing a progression toward the final kinetic energy being closer and closer to the initial kinetic energy (our air track experiment gives an impressive 1% energy loss).
Next, we’ll try to develop an idea of where this energy is going with a bit of a bridging activity. We’ll get out the matter models and talk about what happens as a substance is heated. Since most kids will have had chemistry before, they’ll quickly start talking about molecular motion.
So then we’ll show them these modified dynamics carts which have matter model bumpers. What happens when they collide? We see more random motion, which should give us a pretty good idea of where our missing energy is going.