Mark showed us his circular motion practicum: He has a flying cow toy, which he suspends from the ceiling. After he gets it moving, he measures the radius of its motion using a pair of meter sticks (one along the ceiling, the other held vertically above the cow to mark the radius on the ceiling ruler). Then he times a few revolutions, counting aloud. Finally, he turns the cow off and measures the length of the string holding it up. The question for the students is: given the radius and the length of the string, what is the time on the stopwatch?

After a short break, we charged on into Energy. No one has any idea what energy is, but it's an enormously useful concept. We had read Feynman's Dennis the Menace analogy for homework (which Craig gives his students on the first day of classes) and then played with the Energy Skate Park simulation:

Then, we did two worksheets and whiteboarded them, coming up with some great questions to ask students and ways to link back to previously discussed concepts. Shirley talked about her school's Grand Prix rubber-band car race and some ideas for using rubrics to convey the different levels of mastery. Mark shared an awesome analogy for dissipated energy involving tripping and spilling a huge sack of quarters into the Hudson River: you could send divers after the quarters, but that would cost more than the value of the quarters themselves.

After our qualitative discussion, we talked about developing a common terminology and notation. For the workshop, we're using E

_{mode}for all energy, to emphasize that "energy is energy is energy". Last year, several students had trouble distinguishing between an 'E' and a 'Σ', so I was happy to use Kelly O'Shea's notation instead. This year, I'll see what the text uses and hope I can get my students to draw a proper Σ...

After that, we started the suite of labs that will (so Mark and Craig tell us) show us how to count our energy blocks. Tomorrow we'll finish the labs and discuss Swackhamer's Making Work Work. I'm looking forward to talking about how to fit energy flow diagrams into LOL diagrams and relating those to interaction diagrams/system schema and the system designations we did for the qualitative worksheets.

(In case anyone's curious, I made four pages of notes today, plus writing notes on four worksheet pages.)

## 1 comment:

By that reasoning, then "force is force is force" and any flavor force can be stored as another flavor of force? I'm not buying that using E-sub-something makes that big of a difference since that logic doesn't hold throughout the year.

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