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?
In: Engineering
Because magnets pull (or repel) at all the time, which balances/cancels the forces out. To manipulate/switch their pull periodically (to get uneven forces), you’d need to use electricty to give (some of) them more power, or block them somehow from pulling mechanically (like moving them or putting something between them and the thing that’s being moved — to block the magnetic field).
Which means you’ll be introducing external energy into system, which means it’s not perpetual motion. Which is how electrical engines work. And which are pretty costly in terms of energy you have to add (to get any practical work out).
Also, anything you move with magnets will encounter air resistance and friction and so forth. Which needs extra “kick” to overcome as well. Again, external source of energy, thus not “perpetual”.
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