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Drag and Biomimetics
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NASA Sci Files segment describing how NASA scientists study the natural design of living organisms in order to solve problems in engineering aircraft.
This plane is looking like a winner.
00:00:00
Especially now that we put a rudder on our plane and we moved the wings back.
00:00:02
It doesn't pitch.
00:00:07
And it doesn't bank anymore.
00:00:08
But I wonder if we're still missing something.
00:00:10
Dr. D, we still have a few questions. You think you can help us?
00:00:13
Sure.
00:00:16
Thrust is needed, even when the plane is going at a constant speed.
00:00:17
Why is that? Does it have anything to do with drag?
00:00:21
Yes. Drag is what we call all the forces that act on an aircraft in a backward direction.
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Let's try an experiment.
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I'm going to push this cart. What happens?
00:00:32
It looks like it's not slowing down. But you didn't keep pushing it.
00:00:36
I didn't have to. Isaac Newton explained that once an object gets moving,
00:00:40
it stays moving in a straight line at a constant speed unless you apply a force to it.
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Watch this other cart.
00:00:48
It slows down right away. There must be some force acting on it.
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That's right. An object will only slow down if a force acts on it in the direction opposite to its motion.
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What might that force be?
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It looks like friction. That's the force when you rub two objects together.
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Very good.
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Was an airplane experience friction?
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An airplane experience is a type of drag called air resistance
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because of the air flowing over the wings and other parts of the body.
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Have you ever tried to drive your bicycle into the wind?
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Yes. It's really not very easy.
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You've had some experience with air resistance.
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So if the drag is less, we won't need as much thrust to keep it moving at a constant speed.
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Correct.
00:01:25
So if we can find a way to reduce the air resistance, we've got it made.
00:01:26
That's not exactly right. As it turns out, in addition to air resistance, there's another type of drag.
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This is getting complicated.
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Okay, we'll take air resistance first.
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To understand how to reduce air resistance, it would be best to talk to an expert.
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Of course, the best expert is nature.
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Nature? I wonder what that has to do with drag.
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Well, I know someone who observes nature to understand drag, and he can tell you all about it.
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His name is Ben Anders. He studies birds, fish, and even insects.
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That's our next stop.
00:01:55
Look over there. That man looks like he's studying the fish.
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Dr. Anders, we're the treehouse detectives.
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Oh, hi.
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Dr. D said you could help us.
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We're trying to understand the force of drag.
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Dr. D says you use insects and marine life to help you in your research.
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Yes, I do. When I look at those shapes, I see airplane wings.
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Airplane wings?
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I guess I can see a slight comparison, but why would you want to compare them to airplane wings?
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At NASA, we study birds and insects and marine animals to inspire new research on flight and on ways to reduce drag.
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And we call this biomimetics.
00:02:33
Wow, that's a big word. How do you do that kind of research?
00:02:35
Well, let me ask you this. What do you think has a lower drag, a smooth surface or one with grooves in it?
00:02:39
I'm not sure. I would guess a smooth surface would have less drag, but what's the right answer?
00:02:44
Well, normally a smooth surface does have lower drag,
00:02:49
but if you make the grooves very tiny and you shape them just right, the groove surface has lower drag.
00:02:52
And we discovered that the shark's skin has those exact same tiny grooves to reduce his drag.
00:02:58
I wonder what other secrets he's holding.
00:03:03
This is so cool. I wonder if we need to make some adjustments to our plane to reduce its drag.
00:03:06
Maybe we need to do a little more research.
00:03:11
Let's go back to the treehouse. Bye.
00:03:13
Bye.
00:03:15
- Valoración:
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- Idioma/s:
- Niveles educativos:
- ▼ Mostrar / ocultar niveles
- Nivel Intermedio
- Autor/es:
- Office of Education
- Subido por:
- EducaMadrid
- Licencia:
- Reconocimiento - No comercial - Sin obra derivada
- Visualizaciones:
- 470
- Fecha:
- 28 de mayo de 2007 - 15:32
- Visibilidad:
- Público
- Enlace Relacionado:
- NASAs center for distance learning
- Duración:
- 03′ 18″
- Relación de aspecto:
- 4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
- Resolución:
- 480x360 píxeles
- Tamaño:
- 19.80 MBytes
