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Content Log 093011

Page history last edited by Deborah Hemingway 5 years ago Saved with comment

BERG > Data Collection Page >Fall 2011 Data Collection Schedule


Reflections 093011



Video Time  Classroom content Group 1 content  Group 2 content: Camille, Avery 

JR discussing format of the exam:

two like homework problems

an estimation question

an essay question 

4:40  solutions to the recitations are up     

Avery: what does the essay pertain to?

JR: everything 


We are looking at resistive forces that oppose relative motion of 2 interacting surfaces

Lecture on friction, viscosity, drag 


Student: Do we ever consider static friction on a free body diagram?

Jr: when we are holding a book against the wall, what holds it up? 


two planes, the botom fixed an the top is being pushed

the fluid sticks to each of the plates

the velocity of the fluid changes as a function of distance from the plate 


some good questions in the reading:

the force increases as the plates get closer, why is this?
this is s terrific question, what is the mechanism?

answer is the velocity of the fluid is changing faster when the plates are closer together and so that's why you get this extra effect 

14:18  another question:

viscosity is the fluid to fluid wouldn't there be reaction between solid and fluid and fluid and fluid?

JR: probably yes

we are modeling...the approximation that the fluid sticks perfectly is pretty good, but not perfect


Drag. Different from viscosity is pushing the fluid out from in front of it

depends on density. do you like "d" for density?


C: since it's m over v can you just cancel one of the vs and just put in mass?

JR: that's volume!


C: that was dumb!


JR: We have 3 different kinds of resistive forces

friction - some constant proportional to normal but not the velocity

viscosity - equal to constant times velocity for object

drag - different constant times v squared





 work out the issue of coffee filter

which of these forces is acting on it and how would i know?



story about MIT and "thinking like a physicist"

What does it mean to "think like a physicist"?

What does it mean to "think like a biologist"?

(see my censored reflections here - JS)


I have to tell you that some of biology colleagues get really shirty when I say this and anything I bring up they say, "biologists do this too!"

Some do and most don't. 



09.30.2011_Lecture13_ClassroomView.MOV (21:49:00-30:53:00) (Nature of Physics, Nature of Biology, Nature of the Class)


Start: [21:49]


JR: The reason I want to do this is because... So let me take five minutes and tell the story of why I want to do this.  So... the first time I taught physics for biologists was a 121 class and it was back in like... with your... before your parents were in college--it was 1975.  It really was, wasn't it?  And they... the department, the physics department, sent me to a conference that was being held on how to teach physics for biology students.  It--at MIT.  I was a young faculty member--I think I had just gotten tenure--and so I went to this conference and talked to a lot of medical people, there were medical people there, and biologists who were talking to us about what we should do, teach.  And one of the things that they said was: "Just teach them how to think like a physicist."  


[22:54:00] I have been spending thirty years trying to figure out, "What did they mean by that?"  And I'm just beginning to get an idea, finally, um, but... let me ask you.  You've had, now, enough of this class that you're seeing I'm doing things a little differently than the way they do in your biology classes.  You think?  So what I want to know is: 'What does it mean to think like a physicist?' and 'What does it mean to think like a biologist?'  


And I have to tell you that some of my biology colleagues get very shirty when I say this and anything that I bring up they'll say: "Biologists do this, too!" And some do and most don't.  And when physicists and biologists sit down to talk to each other there's very often a gap because we think about--Arthur actually works regularly with biologists, right?


AL (Pseudonym Needed): Mmhmm.


JR: Am I correct?


AL: Yes.


JR: So... So there is a kind of a gap and it's--I actually believe it's getting less and that physicists are becoming more like biologists and biologists are becoming more like physicists.  But I'm interested in what's your perception at this point.  So what do you- what do you think is different about what I do from what you've seen in your biology classes?  What do we do differently in physics?  (pause)  And there's no right answer to this, right?  There's some--I am asking about your perception.


Pseudonym Jasper (Student 1): I don't know. I'm kind of having trouble seeing a difference.  I guess I just kind of think of it as like they're scientists.


JR: OK. You think it's-you think it's similar.


Pseudonym Sameer (Student 2): I mean, I'm not exactly sure how to explain it but I just think that physicists approach problems differently than biologists do.


JR: And can you try to be specific in some way? Meaning?


Pseudonym Sameer (Student 2): Meaning... I don't really know how... I don't know how a physicist does... but it seems that the way you go about doing a problem does feel different.


JR: Does feel different. OK.


Pseudonym Shaye (Student 3): I actually think it's pretty similar because in both fields you take something you want to look at and break it down into smaller pieces.  And then analyze, you know, each piece, which I think is a similar technique used in both fields.


JR: Good.  That's nice.  Yes.


Pseudonym Camille: Like, going off of that, what I was thinking more so is physicists break down simple models but biologists will just take the actual complicated model and break it down.




JR: I sort of like to think of it that the physicists start from the simple and then try to work their way up and the biologists start from the complex and try to work their way down. Yeah?


Pseudonym Oscar: I was going to say that... I feel there's different ways of thinking about it.  Like, in biology, I feel like if you have a big problem and you think about it a lot more, eventually it'll come to you and you'll have more solutions.  Whereas with physics, if you think about it too much and try to, like, reason it into your head you kind of get a headache.  So (class laughs) you have to, like... you can't think about it so much, you kind of just have to, like... not accept it, but... I don't know... I don't know how to word it.


JR: Just do it. (writing under physics) And here, think about the big picture. (writing under biology) That's what you're saying, yes?  OK?


Pseudonym Sameer: I am probably going to preface this by saying that a lot of biology does deal with numbers, but I do... I will note that with biology a lot of... like the data that we used is a lot more qualitative--like, does it grow?, does it not grow?  Whereas with physics, and maybe to a lesser degree chemistry, we work with a lot of mathematical models and quantitative data.




JR: This is-That's one of the things that my biology colleagues would bristle about.  Arthur?


AL: Am I allowed... allowed to answer, too?


JR: Sure!


AL: So I would say, when I read biology papers there's like... like there's an emphasis on the physicists love models and the biologists love complexity.  But one aspect of when biologists make models they think of them as a simple explanation what explains by complicated data.  Where physicists more obsessed with does this model agree with Newton's laws and does it agree with laws of thermodynamics.  So physicists are more... more likely to collect... connect their model to some basic conservation law or formal physics.




JR: By the way, this Professor La Porta is a biophysicist working in the physics department and he's been feeding me some problems, some things and ideas, that may show up on some of your tests or homeworks later. And here then (working on biology side of board again), connect models to complex data.  Okay?  Cool.  Do we have a couple more?


Pseudonym Jasper: Um... I guess, also in physics we do more things like ideal models--for example, like imagining, like, frictionless surfaces--than we do in biology courses.


JR: Uh... And the example that my biology friend quotes is population dynamics--exponential growth--and there's a lot of simplified models in ecology.  But you don't get so much of that.




Pseudonym Cindy: Um... I feel like in physics, you can kind of look at something, like, on its own, even just the principles, like you can look at just, like the... Newton's first law; but in biology, like, all of the principles rely so much on themselves and, like, every situation relies on something else that you can't, like, look at one aspect of something.


JR: So, harder to separate principles (writing on biology side of board).


Pseudonym Cindy interjects on top of JR: Yeah, like, I feel like Object Egotism wouldn't work in biology.


JR:  Have you had 207, yet?


Class: Yes...


JR: Yes?  Because they... they talk about principles there, but maybe they're not so clean.  Okay.  We got more? Do you want to add more comments?  Yes.




Pseudonym Blair: I want to say that, like, physics is more, like, you, like, memorize equations and then, like, apply to other, like, problems, but biology is more, like, you just memorize the concepts of, like, what's going on and then that's just the end of it.


JR: Okay, so the... the thing I am aiming for, and one of the things that I want to add to this, is that... a thing that happens in physics is that you (writing on the physics side of board) think and reason with equations even when you're asking a qualitative question.


End [00:30:46;25]














Student Responses:


(22:28:00-31:31:00) 25:23:00- Student 1; 25:31:00- Student 2; 25:50:00- Student 3; 26:05:00- Camille; 26:38:00- Oscar; 27:18:00- Sameer; 27:56:00- Arthur; 29:08:00- Student 1; 29:35:00- Cindy; 30:27:00- Blair

Seth not paying attention initially.  Cindy and Tshombe (and the majority of the class) attentive to JR throughout the discussion.

23:27:00- When JR says the "Just teach them how to think like a physicist" line, Seth becomes attentive (turns gaze to JR and focuses on the verbal content).  Seth remains mostly attentive through the rest of the discussion--he looks down at 26:28:00 and keeps his gaze on his desk/notes until he looks up at 27:53:00, but he is still listening, as indicated by his smiles at the 'headache' comment (26:54:00) and the "Just do it comment" (27:03:00).  (And a slight smile for Arthur's problems ending up on tests and homework at 28:53:00.)

Cindy also smiles for the headache comment, but gives her biggest reaction after her contribution to the class discussion--after stating that "...Object Egotism wouldn't work in biology." she gives JR a huge smile (30:00:00)

(Re: 207...  Cindy says "I didn't like that class.  Tshombe responds, "I hated it.")



(23:29:00-32:32:00) 26:24:00- Student 1; 26:32:00- Student 2; 26:50:00- Student 3; 27:06:00- Camille; 27:39:00- Oscar; 28:19:00- Sameer; 28:57:00- Arthur; 30:09:00- Student 1; 30:37:00- Cindy; 31:29:00- Blair

Camille spends this time absentmindedly playing with her hair as she listens and considers the class conversation.  She nods her head in agreement with JR's comment that he is doing things differently than their biology classes (24:56:00).  She  raises her hand to speak at 26:50:00 and waits one turn, speaking at 27:06:00.  At 27:56:00, Camille smiles and laughs at Oscar's 'headache' comment and smiles again at JR's 'Just do it' comment.  When Sameer talks about physics and chemistry dealing with quantitative data, she nods her head (28:38:00).

Avery is actively listening, turning his head and his body to face new speakers.  When JR mentions that Prof. La Porta has been feeding him problems for future tests/homeworks, Avery 'hmphs' (29:53:00).

Other students actively reacting in this segment include Hollis, Oscar and Sameer (all very visible from this camera angle).  Oscar and Sameer nod their heads in agreement with JR's comment that he is doing things a little differently than in their biology classes (24:56:00).  Oscar and Sameer both contribute to the class discussion.  Hollis smiles regularly and laughs for Oscar, JR, Arthur, Student 1, and Cindy.




Jasper: I have trouble seeing the difference


Sameer: the way you go about doing problem


Shaye: similar. in both fields you take something that you look at and break it down into smaller pieces and analyze each piece. I think it's similar


C: like going off of that. physicist break down simple models but biologists take the complicated models and break it down


JR: Physicist start form the simple. Biologists start from the complex


Oscar: if you have the big problem you think about it more (in biology)

if you think too much you get a headache - you have to, like not accept it but...(in physics).


Sameer: a lot of biology does deal with numbers, but the data is more qualitative: does it grow or not grow? more quantitative data in physics.


JR: that is one of the things that my biology colleagues would bristle about (yes- JS)


Arthur - when I read biology paper they think of them as simple explanations





Blair: physics is more memorizing

Biology is more like the concept or what is going on.




JR: I want to add that a thing that happens in physics is that you think and reason with equations even when you are asking a qualitative question

i want to do some of these things with this activity




come up with how you would describe what is happening here

draw the graphs of position velocity and acceleration


Avery and Camille discussing velocity and acceleration

A: gravity is acting on it so it's accelerating constantly



A: why is velocity constant


JR: it looks that way doesn't it - must be demonstrating


A: i thought the change in velocity was insignificant


JR: if its insignificant we will ignore it




what does that mean about forces?

what are the forces

A: drag gravity.





JR: spend 3 minutes, think with the equation and tell me for my 2 resistive forces

what's the difference?


JR: what are the consequences of writing this equation?

you haven't written that equation.




JR: You are writing the definitions those are not equations




solve for the terminal velocity in both cases - all symbols, no numbers

solve if the force is viscous and if the force is drag what do you get?


A: how did you do that?


C: divide by d and it's the square root…


A: how did you get a b down there?


C: oh that's v




JR: We have 2 models, we have 2 competing models



Do it! (drop the coffee filters from 1 and 2 meters to test the predictions of each model)   

C: If this is true they hit the same time.

If this is true they don't hit the same time.

So this one is more true



    C: I have a class to go to!




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