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Eureka! Potential energy (Energia potencial)

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The story so far... Things which are moving have the ability to do work and to apply a force through a distance. They can be said to have "work in" them. Another word for "work in" is energy. Since energy is simply the ability to do work, and since work is measured in joules, energy is also measured in joules. The energy of movement is called kinetic energy. And now... POTENTIAL ENERGY. - Once upon a time, a very small man had to do battle with a very large giant. The only thing that the small man had going for him was his sling. When he loosed it, the mass of the stone combined with speed to give it kinetic energy, with which he was able to do work on the giant. thereby applying force and exerting that force through a distance. The stone had energy thanks to its movement. Indeed, everything that moves has energy. Even the air around us. Once air is moving it has the energy to drive wind mills. Just as when water is moving, it has the energy to drive water mills. But every moving thing has kinetic energy. Does that mean that tings which aren't moving don't have energy? In that case, why are you staring up at that rock fixed on the edge of the cliff? Why be frightened of it? It can’t have any kinetic energy because it’s not moving. And if it hasn’t any kinetic energy, it can’t do any work on you, can it? But maybe you’d better move out of the way all the same. Why? Because of the rock’s position on the edge of the cliff. It hasn’t any movement so far, but it looks as if it’s on the point of having quite a lot of movement any minute now because the force of gravity wants very much to make it fall off the cliff. That means that, in a sense, the rock has a lot of energy stored upon it. A lot of what scientists call potential energy or the energy of position. The slightest puff of wind, and that potential energy will immediately start being transformed into kinetic energy. That’s how the energy of position becomes the energy of movement. Oh-oh... don’t look now! But it’s time to use some more kinetic energy to do some more work on that giant. Oops! Hold on, what’s happening? Let’s do that again in slow motion. The stone lost more and more speed as it left the sling because of the force of gravity trying to pull it down. The higher it got, the slower it went and the less kinetic energy it had, until at last it came to a complete stop and had no kinetic energy left in it at all! And, therefore, no work in it, and no force that it could exert on the giant. But where did all that kinetic energy go? Is it lost forever? No. It’s been transformed into potential energy. The work that the little man put into slinging the stone is now stored up in the stone. But of course, in reality, the stone only stops for a split second and then immediately starts coming down again until it has got back all the kinetic energy that it had in the first place. Meanwhile, back at the cliff edge, the giant finds all this very amusing. But he’d better watch out! Because most of the kinetic energy it took for him to climb up to the top of the cliff is now stored in him by virtue of his position. He’s full of potential energy just waiting to be converted back into kinetic energy any minute now.

Video Details

Duration: 4 minutes and 52 seconds
Country: United States
Language: English
Views: 239
Posted by: lorena3 on Dec 20, 2010

Petit video animat que explica de manera molt aclaridora en que consisteix l'energia potencial.

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