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So today I am going to do everyone’s favorite non Newtonian experiment.
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I am going to put this corn starch and water solution on this speaker, but I want to do
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this scientifically.
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So I am shooting it with a high speed camera and I am going to vary the frequency and the
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amplitude and see what factors really give us the best corn starch monster.
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It still very much looks like a liquid at this point, but as I increase the amplitude,
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you can kind of tell that it is not moving as smoothing as it should anymore.
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You can see at this amplitude it starts to jump around a little bit.
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Now I want to try to increase the frequency and
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see what effect that has.
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You are now at about 20 hertz, which is the frequency recommended by some scientific papers
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that have studied this phenomenon.
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I’ll up the amplitude a little bit.
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That is incredible.
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That is awesome.
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Now I am going up to about 22 hertz, seeing nicer structures.
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But it is really tough to tell, because it is somewhat random.
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Sometimes it just turns into a blob like that and other times you get some really cool things
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forming.
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I am about 34 hertz here and we are not seeing a lot of structure.
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It seems like at these higher frequencies it just sort of turns into a blob.
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Interesting how it becomes more coherent and smoother actually at the higher frequencies.
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Wow.
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That’s interesting.
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In the high speed you can clearly see that the inertia of the thing is keeping it off
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the speaker entirely.
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That is really cool.
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So it is just getting kind of bumped with that frequency.
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It is not really sticking around.
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That this why you probably need a lower frequency.
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Oh.
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Well, that is the end of that.
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So how do non Newtonian fluids work?
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Well, the corn starch and water is really a suspension.
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That is, these tiny little grains of starch suspended in water.
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So when you try to move that fluid slowly the starch has time to get out of the way
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of each other, because it is lubricated by all those water molecules in between.
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But if you try to get it to go fast—and that is, there is a lot of sheer, which means
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there are some places that are going faster than others—well, then all of the starch
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grains kind of get stuck up against each other.
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And they can’t flow past each other.
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So at that point it becomes like a solid and less like a liquid.
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You know, this kind of reminds me of traffic in LA where I have been recently.
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If there are not that many cars on the road it is basically like having a small amount
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of starch particles in your water and everything flows very smoothly, but as soon as you get
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to rush hour and you have some cars which are trying to floor I down the highway, plus
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there is all of these cars, which are like our starch particles, on the high way, then
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suddenly everything gets clogged and you are basically in what is a solid.
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So traffic might be an example of something that is an non Newtonian fluid.
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It flows very well when there aren’t very many particles or when it is going quite slowly,
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but as you try to increase the number of cars and go really fast, then everything kind of
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gets clogged up.