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Hello everyone.
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This problem, we're told that in one second, an electric fan converts one joules of energy, of electrical energy, into the kinetic energy of air at its first level.
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Then once you increase the speed of the fan, it now propels two times as much air at two times the speed.
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Okay, so this is at level two.
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And the question is, how much energy is the electric fan transforming into the kinetic energy of air in this case.
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So we look at what happens at level one.
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We have some air, some mass for the air, because there is a given amount of air that it pushes through.
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And this can be effectively modeled as having mass am air.
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It has some speed, which we can model or we can call the velocity or speed of air, v -air.
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Okay.
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This gives rise to a kinetic energy at level one, which is a half times m -air times v -air squared.
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And we know that this is equal to one jule...