Can magnetic energy be used to create a magnetic motor which can power vehicles and machines?
closed as unclear what you're asking by Dilaton, Chris White, Waffle's Crazy Peanut, John Rennie, Emilio Pisanty Aug 23 '13 at 13:32
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Contrary to what we might want to believe, any kind of perpetual motion device would violate the known laws of physics. No system can create energy out of nothing, and even if an engine were 100% efficient and didn't lose anything to friction, gravity, etc, it might run forever as long as there was no draw of energy out (ie. to do useful work). As nice as it would be to have such a machine, Ray Bradbury said it best, "There ain't no such thing as a free lunch."
As to your question about water powering a car, that too would violate the known laws of physics. Water is an extremely stable compound, and is not combustible at all. In order to derive energy out of the components of water, the water molecules would have to be split into their constituent parts, oxygen and hydrogen. The hydrogen would be combustible, recombining with oxygen in the atmosphere to generate energy and water as exhaust. However, the amount of energy required to split off the hydrogen from the water is significantly greater than the amount of energy you could derive from burning the hydrogen. Once again, in order to do useful work, we have to have an external energy source.