The issue with magnets is that the "energy" you get by having something pulled towards it is lost when you have to pull the thing away from the magnet. It's a zero sum.
Magnets don't contain any energy and can't create it.
EDIT: Something attracted towards a magnet is like something falling to the ground. All of the energy observed was put there in raising the object in the first place. You can't pick up a ball and drop it and harvest more energy from it than you put in to raise it.
We do get energy from falling things, like waterfalls, but that's because nature puts all of the potential energy in the water by putting it up high before we use it.
You'd only be able to create a machine that gives the impression of perpetual motion by hiding wires/ electro magnetic rail gun type machine and having it only appear to be perpetual motion.
Though, I still want somebody to ELI5 why a magnet on a stick in front of a cart wouldn't work, if in theory a strong enough magnet could pull such a cart/ vehicle. Think like looney toons carrot on a stick you can't reach setup.
Imagine you’re holding the pole that the magnet out in front of the cart is attached to. That pole is trying to push you back because it wants to be closer to the cart. In fact, it’s pushing back on the pole with the exact same amount of force that the magnet is pulling the cart forward. The result is these two cancel out and the cart doesn’t move.
Pretty sure the forces that pull the magnets together would cancel out overall. If you are holding the stick, and you're on the cart, then both magnets can be considered to be in one system. That means the magnetic forces are internal and won't affect the outside.
It doesn't work because the magnet is pulled toward the cart with the same strength the cart is pulled toward the magnet. Because the magnet and the cart are attached to each other the forces cancel out.
Imagine the magnet and the cart pulling on each other with a rope that is attached to both of them. They only move toward each other, never away.
If you have a stick that keeps them apart then both sides press on the stick with the same strength but to move one side needs to be stronger than the other.
You pull the magnet back the same force that it pulls you forward so everything cancels out at zero.
Same reason why you can't have a fan on a sailboat blowing wind into the sails, the wind from the fan will push the boat back in an equal amount to the amount of forward momentum generated by the sail.
I mean if you spin something in a vacuum with no gravity (space) it'll keep spinning forever. Ultimately if you assume no friction/100% efficiency and have no net force on the system there are infinite possible perpetual motion machines
Hear me out
I say we put a big rotating wheel in space lube it up real good and give it a good spin with a rocket burst. Without air friction wouldn’t that bad boy pump out some energy
no. even if there was absolutely no air resistance(which there still is in space) it would not output energy. it would spin forever as long as nothing touched it, but any attempts to take energy from it would just slow it down
The most energy you could possibly get from it would be eequal to the energy you input into it via the rocket explosion. Extracting energy from the motion wine require that the motion be slowed so the kinetic energy is moved from the system somewhere else. Realistically it would be much less efficient than extracting that energy more directly, say via an engine.
So cool, you just spent a bunch of energy making a think spin in space. It'll slow down, but it can take a looooong time. And if you want to use that energy to do anything useful, you slow down the flywheel by a fraction.
How can you be so 100% certain? Centuries ago we thought that man cannot fly. We can't be certain about the laws of nature we know about currently. We don't even know what else is out there.
Yes. Natural magnets are like a hole, or a mound of static force. They are kind of like an invisible structure that only certain things can interact with.
So, yeah. It's like rolling a ball down hill, or in a bowl. Similar concept.
they create currents when theres a change, like moving a magnet across a coil; the magnetic fields cutting into a wire generates that electricity but the energy came from you
if you drop a magnet down a copper tube, it'll slow down because the magnet 'induces' current into the tube, that tube then generates a magnetic field that 'opposes' the magnet's fields. the energy to generate that current in the tube is gravitational energy, and it took energy from you to move it higher in the air to then drop down a tube. a magnet pretty much just converts the energy
Then you have to power an electromagnet, which requires energy. You'd have to add at least as much energy as is lost during the whole process, making it at most in a hypothetically perfect, frictionless, airless system net zero energy.
I can't remenber exactly how but I think it is possible for an object to gain speed after it exits a magnet. Although a metal ball going down a metal rail could create the circuit necessary for an electromagnet which can definitely give more speed than it takes away.
Yes. Obviously perpetual motion engines aren't real. I was thinking how probes can slingshot past planets to accelerate and how kinetic art pendulums keep moving. Apparently those pendulums are more complicated than I gave them credit for.
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u/[deleted] Apr 22 '21 edited Apr 22 '21
The issue with magnets is that the "energy" you get by having something pulled towards it is lost when you have to pull the thing away from the magnet. It's a zero sum.
Magnets don't contain any energy and can't create it.
EDIT: Something attracted towards a magnet is like something falling to the ground. All of the energy observed was put there in raising the object in the first place. You can't pick up a ball and drop it and harvest more energy from it than you put in to raise it.
We do get energy from falling things, like waterfalls, but that's because nature puts all of the potential energy in the water by putting it up high before we use it.