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There are many videos on youtube in which people arranged magnets in circle and rotated one placing in middle of that circle on a shaft, and the magnet (magnet motor) starts madly and continues its movement.
Do they really rotate infinitely?
If so, do they from where they get that extra energy to move so fast and infinitely?

EDIT: This question is about real world scenario

UPDATE: I am unable to find that particular video about which i talked about -- I added them to my favourites, but they are all now deleted :( -- there are hundreds of that that kind of videos. Some example videos links
http://www.youtube.com/watch?v=dT9s33X9D4I
http://www.youtube.com/watch?v=yei0NMqUaZ8
http://www.youtube.com/watch?v=5DvPLFX5gwA
http://www.youtube.com/watch?v=i0oUaPZ_wF8
http://peswiki.com/index.php/OS:Screw-Magnet_Motor
http://www.youtube.com/watch?v=aHVBu77jz4w

SMUsamaShah
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4 Answers4

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Anything can rotate infinitely, if there is no friction. Rotating an object with constant velocity uses no energy to maintain. With friction it will loose energy and eventually stop. If you add a static magnetic field to the object, it will gain some finite potential energy, which in turn can be converted to kinetic energy.

Now if you add a changing magnetic field, you can make it continuously rotate or even accelerate, but this requires energy to maintain. This is how regular electromotors work, the battery is an electromagnetic potential, and will give the motor kinetic energy, but eventually the battery will be depleted.

TROLLHUNTER
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5

Looking at the first video -- if magnetism was sharply directional (i.e. a little searchlight of attraction coming out from the tip of the magnet) then this device would work. Unfortunately magnetism is (roughly) an omni-directional field and so doesn't just let go of one screw and start tugging on the next. The field attracts strongest the objects that are closer and attracts more weakly the objects that are farther away. If you make the magnet strong enough to start pulling at the screw-head that is next in line it will be strong enough to pull very strongly at the screw-head that is passing under it.

The person who built this wants a force to be applied to the drum at a tangent to the surface of the drum (kind of like a rope wrapped around it) to spin the drum. But any force applied by the magnet is going to be nearly straight out, which won't induce a tendency to spin.

The proof comes from the fact that the device doesn't self-start. When the magnets are brought close to the drum the drum jiggles a bit as it comes to a static resting place, but the supposed spinning force doesn't happen -- the narrator has to start it spinning.

David Rouse
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3

As this was made the source of a duplicate declaration I will answer here, because the answers existing, though correct may not be clear enough.

What are permanent magnets? They are solid matter in lattices where the individual magnetic moments of atoms became aligned when, due to high temperatures matter was in a liquid form. An external magnetic field imposed by the fields existing during the creation of the planet, aligned the dipoles while the system cooled and crystalized.

These primordial fields may be due to a dynamo effect, like the one that exists in the sun presently, or some fields carried by the plasma that coagulated to form finally the earth. In origin the energy existing and creating the solar system comes from the cosmological creation of the universe, as in the big bang model.

These magnetic materials, permanent magnets, are storing magnetic energy , the way a battery stores electrical energy.

All these perpetual motion proposals using magnets , are transforming magnetically stored energy to kinetic energy and eventually the magnets will demagnetize. Even if in space in a perpetual motion, because of radiation due to friction in mechanical parts the magnets will demagnetize. This will happen faster if energy is extracted for use.

anna v
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Not without some sort of external power source. Extremely low power neodymium magnet pulse motors are a reality though, and can be powered from the ambient energy in the environment.

EDIT: has to be said though, that extremely low power magnet motors are more like electromechanical oscillators than motors.

Janne808
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