Eli5: why cant we use magnets to make an infinitely spinning thing to get infinite energy


-english is not my first language-

Edit: alot of people think im referring to motors or generators or some sorts. But I mean something like this:


I know its probably fake and not possible but I want to know why and how

In: 0

Magnets and electromagnets are used to make spinning things. These are things called motors and is used nearly everywhere (washing machines, cars, etc etc) In order to make the motor spin, energy has to be injected into it and the resulting output is a spinning rotor which has kinetic energy.

Magnets are also used to create electrical energy. These are called generators. In this case, some external energy source (wind, water behind a dam, steam etc) is used to spin the rotor and results is the conversion of that energy into electrical energy as output.

Neither the motor or generator are 100% efficient. The amount of energy put in is less than the energy released. Some energy is always lost due to friction, heat, sound etc. So even if you hooked a motor to a generator and used to generator output to run the motor, it would not work for long and there is definitely no way to make excess energy.

Magnets have a feature called cogging torque. It’s helpful to imagine magnets arranged in a way where you would think they could spin infinitely as like gears. There is a point where the magnets fall into a place where an equal amount of force if needed to pull or pull them in either direction to get past the “next tooth in the gear” to continue moving.

Captain Disillusion has an excellent video that provide a visual explanation of this: https://youtu.be/sT_bTnkwLuE

Why not use the wieght of the magnet to make a thing move, like a perpetual motion machine?

Simply put, because it’s impossible. Why? If it was possible, it would contradict the law of conservation of energy https://en.m.wikipedia.org/wiki/Conservation_of_energy.

This is how you can immediately dismiss any intricate “inventions” that claim infinite energy production without the need to debunk each one of them individually let alone get into nitty gritty details to point out the flaw in the logic.

Conservation of energy law itself by necessity follows from the symmetry of our space-time continuum towards the time translation.

In other words — in the universe we live in perpetual motion machines (of the first kind, that produces energy from nowhere) _cannot exist_. End of story.

There is an experimental coalmine truck. It is electric and drives empty uphill to the mine to get loaded. Once its full it a dynamo is added to harvest energy whil it deives downhill. All the extra weight makes the creation of energy possible. This fills the batterys for the drive back up to the mine.

I can take a magnet and put it on a shaft. Will it spin? No, because there is nothing pushing it around. So I place a magnet nearby, with its north pole facing the north pole of the magnet on the shaft. The poles repel and so the free magnet rotates to move its north pole away. Hooray! But after half a turn the south pole of the rotating magnet is facing the north pole of the fixed magnet, so they attract. What happens as the rotating magnet passes beyond half a turn? Instead of being pushed further round, it is actually slowed down by the attraction and so comes to a halt.

Could we get round this by reversing the fixed magnet? Yes we could – by flipping it round or by making it an electromagnet and reversing the current. The problem is that we are doing these things near to that rotating magnet. Just as the rotating magnet is pulled and pushed by the fixed magnet, the fixed magnet is pulled and pushed by the rotating magnet. To flip it round takes some effort, and in fact it takes exactly the same amount of effort as the amount of energy you get out of the spinning magnet. It is a bit harder to explain why using an electromagnet also results in putting just as much energy in as you get out: this exactly what we do in a motor.

Anyway, the simple answer is: r/ThatsPerpetualMotion

Because magnetism is what’s called a conservative force where returning to a position means no work has been done in the time between being at those points. That means your spinning wheel is doing producing no energy as it spins. Also since we’re in the real world there are also non-conservative forces like friction that are expending energy you don’t get back when you return to the same position, so you’re always losing energy.

Some other conservative forces you’ve seen would be spring tension and gravity. Once you set it in motion a spring keep moving “for free” since a cycle uses no energy and it only slows down as friction saps away the energy. In the same way, if you throw a ball up its kinetic energy turns into gravitational potential energy and then back into kinetic energy and (ignoring friction again) it has the same speed when it returns to the height it left your hand–no energy left the ball the whole time.

you can and you do, this is the core principal for electrical motors and Generators.

the issue is more about defeating the inherent inneficiency so that you can have a net positive afterwards you still need to introduce energy ot the system ot have the core spin so it can take advantage of the magnets.

even if you had this motor setup to feed itself the resulting output would be a net negative and it would eventually stop(if this were not the case then there would be a violation of the principle of energy conservation)

Lenz’s Law is the electromagnetic equalavent of Newton’s 3rd law paraphrased as “Every action has an equal and opposite reaction”.

Lenz’s Law: The current induced in a circuit due to a change in a magnetic field is directed to oppose the change in flux and to exert a mechanical force which opposes the motion.

What does this mean? It means that the induction of your spinning magnet will produce a counter-electromotive force or Back EMF which will cause the spinning magnet to slow down as it produces current.

Magnets dont do work.

Glue a magnet to ceiling and put something hanging on magnet. It does as much energy as you screw a hook to ceiling and hang something onto it.

It is 100% possible. I worked on the device from the age of 10-17. Found an endorser to sponsor me to the point of production and during the patent process was issued a SAD. So I stopped and destroyed everything knowing what could potentially happen otherwise. It requires the use of electromagnets to prevent the magnets from achieving a locked in place position. The reason we don’t have perpetual motors or free energy generators is because they would destroy our economy. Millions of jobs would be lost because such a device eliminates the needs of countless other devices we currently depend on. Money makes the world go round and as long as greed is a factor we will never reach our full potential as a society.