5K(in car) -->5T(in chair) --> 4K(in car) + 1T(in chair).
At least one teacher picks up this idea. They recognize that the car stops and they are trying to account for the energy. They make the suggestion that the energy turns into thermal because - I am making a big claim here - the teachers in this video struggled to figure out what the hidden energy was last year, and found that it was thermal, so here they are just assuming that the energy is thermal because they can't see it. (SAM SAM SAM - this is golden). I LOVE how Stamatis is quiet during the entire idea presented. He is totally patient. :) Here is the video:
Video 1
After this, Stamatis has been silent for the entire conversations, but then he asks a wonderful question.
"What process takes thermal energy and turns it into kinetic energy?"
This spurs the teachers to think about what happened in terms of what they know about physical processes and what is possible. They mention firecrackers, but Stamatis points out that there are no explosions (I am paraphrasing) in the collision with the mousetrap car and the chair.
Video 2
Kim brings up squash balls and how you have to add thermal energy by rubbing them on the floor to get them to bounce well. So she is justifying the thermal energy as a reason for the bounce,
The whole time Akbar is silent but is getting more and more "wiggly" moving around, touching his head, and then he speaks in the next segment. He talks about the squash ball rubbing making the ball more elastic - so the elastic energy is what is used to bounce the car off the chair.
Video 3
Finally, the group looks at it again and Kim is surprised that they had originally said thermal.
Kim: "Did we say that?"
Jessica: "We did say it. We said 5 people would all become thermal energy. We totally said it."
It is like Kim has completely forgotten what she suggested a few minutes earlier! What does this mean for the retention of the conversations going on in a classroom? OR does this mean that she is actually not meaning all thermal in this scenario? I think she might have been saying all thermal because she thinks of it as stopping at the chair. ...? She said earlier (Video 1) that only a little bit of bounce back occurs. Perhaps she is thinking of this as a really small amount of bounce?
Video 4
One last comment - Check out the interaction that Sam has with this group - HIS group, when Stamatis is there engaging with the group.
Here are the names of those videos:
ReplyDelete1. E2 120807 1142 Mic3.Section.A.WeSayThat
2. E2 120807 1142 Mic3.Section.B.1.IsThatPossible
3. E2 120807 1142 Mic3.Section.B.2.Maybe.This
4. E2 120807 1142 Mic3.Section.B.3.DidWeSayThat
Abby, this is really cool. In this case, elastic energy is another example of "imperceptible" energy because the compression happens so fast that you can't see it.
ReplyDeleteMy interpretation is not that Kim "forgot" what they had said, but that she really wasn't thinking about the moment when it turned around. Jessica did say that all the people turned to thermal in that moment, but my guess is that Kim was so focused on figuring out the difference between their two scenarios (car going back a little bit slower vs. car going back a lot slower), that she didn't really hear Kim say this or understand its implications, so it's not surprising that she doesn't remember it later. I actually didn't hear it the first time I watched the video, and had to go back and watch it again.
Hm. I just watched Video 1 again, and Kim is the first to recommend all five jumping into the chair as "heat" when the car hit the chair, both with her body first, then explaining it again afterwards. Then Jessica also accepts that idea that they all are thermal energy in the chair for a bit. She suggests the heat idea, and then explains it, and then listens to someone else use it. So I want you to watch that video again and see if you agree with me!
ReplyDeleteAbby, I love that when they are pushed to think about process, they seem to start to really sense-make about _this_ scenario.
ReplyDeleteDid you notice in Video 3 when Jessica talks about the usefulness of thermal energy?
And my interpretation of Kim's surprise in the last video is not that she forgot that she said something, but that she didn't understand (or wasn't paying attention to) what Stamatis said. But I only saw pieces.