The groups were asked to simulate transformation from kinetic energy to thermal energy (K->T), which was done by pushing one of the walls of the box, decreasing the volume, so that the temperature of the gas increased.
Now, Stamatis argued that the particles each have kinetic energy and that their total kinetic energy is the kinetic energy of the gas. At the same time, the gas has a certain temperature, which is associated to thermal energy. What is the relationship between the two concepts? Sid and Debra admit to being confused.
Next, at a metalevel, Sid realises that their idea of kinetic energy referring to bulk movement only was a working hypothesis in class, but that it may not be the case. Stamatis sums up that they now seem to agree upon what the question is, namely the relationship between thermal and kinetic energy, but that they do not have the answer yet.
As a reflection, another twist to the situation is that also potential energy may add to the thermal energy (e.g. potential energy of the vibrations of polyatomic molecules, but luckily this is hidden in the ideal gas scenario). Start of the Wikipedia entry: "
Another theme: Gradually more people joined the discussion!
Oh, the physics rabbit hole does go deep. Beware of asking too many questions, or else you may find yourself at a place with no answers.
ReplyDeleteI love that E2 is bringing to teachers' awareness the intersection of kinetic and thermal energy. By analogy, it's almost like trying to understand the transition from quantum mechanics to classical mechanics (which also might be controlled by thermal energy! but let's not go there). The first layer of diagramming energy problems is to sweep challenging features like sound, heating, and energy dissipation under the rug; i.e. call it all thermal energy. In a sense, you ignore some really cool physics, but at least you can begin to resolve some scenarios.
But the next layer demands that you look each of those effects in the face. It demands that you actually try to understand some real physics and not hide behind broad generalizations. Great conversation that I wish I could join in on.
There's a piece of me that really wants to unpack Sid's comment toward the beginning of the second video: that she would never have come up with that sentence on the whiteboard. Stamatis points out that those are her words, and she agrees, but she doesn't recognize them as her own. Does anyone have an interpretation of what this means?
ReplyDeleteThe sentences are typical textbook descriptions/definitions of energy: "Temperature is the average kinetic (or thermal) energy of the particles." I interpret Sid as saying that she, personally, would not describe temperature in these ways.
DeleteShe also says "they are totally wrong". This may relate to a handout they got of Kraus/Vokos on language of heat energy, saying that most shorthand descriptions of 'energy', e.g. the ability to perform work, are misleading.
However, I am not sure why the thinks the idea of temperature as average thermal/kinetic energy is wrong. It is accurate in the kinetic theory of gas (although not as fundamental as 1/T=dS/dU, given fixed N,V)
Hm. But Stamatis says that the sentence on the board "were her words" (2:03). And Sid agrees. What does that mean if she also says that she never would have come up with the sentence?
DeleteI think she copied the statement from a textbook-like text and uttered it (as in her words), but would not spontaneously have come up with it herself.
DeleteI consider that Stamatis saying are here words means she said those exacts words. But for me the lack of identification with the sentence, and I think it is also Jesper interpretation, is a reflection of here not owning that concept in that way. For me it would be an indicator of memorization rather than understanding on what it means. She is still looking for a way to define it in a way that she can identify with that definition.
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