If I turn my fan on and 100% of the electricity is converted to heat, where does the kinetic energy of moving fan blades come from? Even the Trump administration cannot just repeal the law of conservation of energy.

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numb7rs 2 days ago | parent | next [-]

Even if most of the energy goes into kinetic energy of the air, that air will lose momentum via turbulence and friction with the surrounding air, which will end up as... heat.

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jo909 2 days ago | parent | prev [-]

While spinning, the blades store a miniscule amount of kinetic energy.

After removing power even that small amount ends up as heat through friction ( both in the bearing but mostly in the air turbulence). And the blades end up in the same zero energy state: sitting still.

So it is correct that a 100% "end up" as heat

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usrnm 2 days ago | parent [-]

Most of that energy gets transfered to the air that's being moved by the blades, and who knows what that air does eventually. And we're not even talking about the plant growing light that might be sitting in my room near my house plants literally creating new life from electricity.

	▲	stouset a day ago \| parent [-]
		> who knows what that air does eventually We do know what that air does eventually. Given no further inputs of energy, it swirls around generating friction, raising its temperature (heat!) as the currents slow down to nearly nothing.