For the second class, we used a model developed as Washington State University as part of the Energy Project called Energy Theater. The idea is to model a system entirely through its energy units, with those energy units being continued in parts in the system but able to transfer between parts and transform between energy types. This was our first outside session at the base of the UCSD Snake Path.
We again started with a pre-assessment to start thinking about types of energy, types of energy transformation, and energy conservation. Then we had a brief discussion of the rules:
- Everyone represents a unit of energy which remains the same amount of energy throughout the simulation
- Energy cannot be created or destroyed, but it can be transformed
- You can only be one form of energy at any one time, and you must clearly signify what form of energy you are.
We started out by modeling me throwing a poster board that slides to a stop on the ground. The students first sketched out the parts of the system (me, the poster board, and the ground; some also included the air) and the forms of energy present (chemical potential in my muscles, kinetic of the board, heat on the ground and board, and radiation). We spent some time discussion these elements, and also the transformations that occur at different points – this was to be our script.
The students then made their costumes, using balloons, paper, streamers and pipe cleaners. This was fun!
We then rehearsed, walking through the system, starting off as my potential energy, then transforming into kinetic in the board, and then allowing that energy to slowly leak away as heat in the ground and board as the board came to a stop (with some units transforming further to radiation). It took a little bit of practice to get this to be natural, but a lot of good questions came up about the forms of energy and the transformations.
Next, the students had to model a different system: an incandescent lightbulb steadily glowing. The system included the socket, wires, bulb with tungsten filament, and the area around the bulb. They got 15 minutes to negotiate their simulation, and the addition of electrical energy made this a challenge even for the physics majors/graduates. One important realization is that the electrons must maintain their kinetic energy, and they don’t slow down (and pile up) in the filament; its the electrical potential that is transformed at the filament. This led to a lot of discussion about what electrical potential actually is and how its made. There was also some discussion about whether at the tungsten resistor heat created radiation or vice-versa. Some challenging physics concepts were definitely addressed!
In the post-assessment, students commented:
“I learned that e- also carry potential energy”
“It surprised me how potential and kinetic energy was coupled in the light bulb”
“Understanding the movement of energy surprised me. Recognizing that some of it transfers from object to object, and some of it stays in the object but transforms.”
“What surprised me was that in the case of the light bulb potential energy moves with kinetic energy to keep an electron moving to prevent a pile up.”
“I want to know more about the relationship of potential and kinetic energy in the system of an engine moving a car”