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Work and Energy

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Subido el 28 de mayo de 2007 por EducaMadrid

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NASA Sci Files segment explaining energy and work.

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It takes energy to do work. 00:00:00
Energy comes in a variety of forms. 00:00:02
The powder in this funnel has potential energy. 00:00:04
It's changed into heat energy when I blow it through this flame. 00:00:07
If I do work and use my energy to stretch this giant slingshot, 00:00:14
the energy is stored as elastic potential energy. 00:00:18
And when I let go, the energy is changed into energy of motion, or kinetic energy. 00:00:22
Finally! 00:00:28
Flexiglass did the work to stop the tomato. 00:00:30
It takes a lot of work to lift this 25-kilogram anvil. 00:00:33
I have to overcome the pull of gravity. 00:00:36
The anvil now has a lot of gravitational potential energy. 00:00:38
This poor cantaloupe will be smashed when I release the energy by letting go. 00:00:42
Hi, Dr. D. 00:00:53
That was a great show. 00:00:54
I really like the experiments. 00:00:56
Thanks. 00:00:58
By the way, are you working on any projects? 00:00:59
Well, Jacob has broken his foot, 00:01:01
so we're trying to figure out a way to get him back into the treehouse. 00:01:03
We think we can lift him with a rope, if we all work together. 00:01:07
Let's talk a little bit about work. 00:01:10
First, you have to have a force, a push or a pull. 00:01:12
The force alone is not enough. 00:01:15
To do work, the force must be applied through a distance. 00:01:17
Here, hold onto this anvil for me. 00:01:20
Sure, but why? 00:01:23
Why? 00:01:26
Getting tired yet? 00:01:32
You bet. 00:01:33
Because you haven't moved the anvil, you haven't done any work. 00:01:34
Doing work and getting tired are not necessarily the same thing. 00:01:38
Can we put this thing down? 00:01:42
Of course. 00:01:44
Now with the slingshot, I did work when I pulled on the strap 00:01:45
and moved it back about one meter. 00:01:49
When I let go of the strap, the slingshot did work on the tomato 00:01:51
because I pushed it forward and sped it up. 00:01:54
I love the slap. 00:01:56
Now with the 25-kilogram anvil, 00:01:58
I had to supply a force of about 55 pounds, 00:02:00
going against gravity as I picked it up. 00:02:03
The higher I lifted the anvil, the more work I did 00:02:05
and the more gravitational energy the anvil had. 00:02:08
Then the anvil must have had a lot of energy 00:02:11
because it sure crushed the cantaloupe. 00:02:13
But Jacob is heavier than 55 pounds. 00:02:15
Does that mean it would take more work to lift him? 00:02:18
Yes, that's right. 00:02:20
Since work is equal to force times distance, 00:02:21
increasing either the force or the distance will require more work. 00:02:23
You said it took energy to do work. 00:02:27
So where did the energy come from to lift the anvil? 00:02:29
The energy came from the corn flakes I had for breakfast this morning. 00:02:32
Corn gets energy from the sun. 00:02:35
It's going to take a lot of energy to lift Jacob into the treehouse. 00:02:37
I think it's going to take all our energy to do the job. 00:02:40
Thanks, Dr. D. 00:02:43
You're welcome. 00:02:44
Bye. 00:02:45
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Idioma/s:
en
Niveles educativos:
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      • Nivel Intermedio
Autor/es:
NASA LaRC Office of Education
Subido por:
EducaMadrid
Licencia:
Reconocimiento - No comercial - Sin obra derivada
Visualizaciones:
531
Fecha:
28 de mayo de 2007 - 15:32
Visibilidad:
Público
Enlace Relacionado:
NASAs center for distance learning
Duración:
02′ 46″
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:
16.77 MBytes

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