why can’t we use magnets for perpetual motion?

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I mean, I always used to fancy as a kid why can’t we use magnets to keep a fan going in circles? Why can”t we create a perpetual machine using magnets? Even if the magnets get worn out, we can still use them for considerable time. What is the science behind it that makes it impossible?

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19 Answers

Anonymous 0 Comments

How would it work? Once the fan turned a quarter turn or however much it took to align the magnets, it would just stop. Even with a perfectly zero friction axle for the fan (also impossible) you *still* can’t get a fan spinning continuously with magnets unless the magnets are either moving or switching on and off. And of course either of those requires energy input, so by definition that’s not perpetual motion.

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