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Topic: Magnet Motor (Read 888 times) |
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Sir Col
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Perhaps it is time to rewrite the physics books! 
In the diagram, a collection of magnets with their north pole pointing outwards, are attached to a wheel at 45o to the tangent.
Another magnet is attached to a fixed surface below the wheel with its north pole pointing upwards, and angled at 45o to the horizontal.
As the system is released, the two magnets (within magnetic proximity) repel each other, causing the wheel to rotate with sufficient momentum so that the next magnet, in passing over the fixed magnet, is also repelled.
This process continues indefinitely, creating the world's first perpetual motor... or is it?
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Grimbal
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Re: Magnet Motor
« Reply #1 on: Jun 14th, 2004, 4:45pm » |
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Is this an example of Sir-Col-ar reasoning? 
::Magnets also repel sideways. Just imagine a little spring between the gray parts, from the time they approach to the time they part again.::
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rmsgrey
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Re: Magnet Motor
« Reply #2 on: Jun 15th, 2004, 6:18am » |
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Could someone explain how the magnet coming towards closest approach doesn't use up (to a first approximation) as much energy as is given back as it moves away again?
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Sameer
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Re: Magnet Motor
« Reply #3 on: Jun 15th, 2004, 9:00am » |
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I don't know if my explanation is right, but here goes nothing!!
In order for a system to oscillate (or rotate in this case) we need a loop gain of > 1. Obviously this system doesn't.
Look at it this way. Consider a center point in between the two magnets on the wheel. According to symmetry this point experiences no force as the force of repelsion between bottom magnet and those magnets left and right to it on wheel are same. Considering this fact, to overcome the repelling of left magnet the right magnet must provide a force at least twice. Contradiction. In mathematical terms if G is forward gain and H is feedback gain here GH=1 hence non oscillating.
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"Obvious" is the most dangerous word in mathematics.
--Bell, Eric Temple
Proof is an idol before which the mathematician tortures himself.
Sir Arthur Eddington, quoted in Bridges to Infinity
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Icarus
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Re: Magnet Motor
« Reply #4 on: Jun 21st, 2004, 5:21pm » |
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I had this conversation with my father many times. He conceived of exactly this configuration and was absolutely convinced it would work (he even attempted to build it once). I tried over and over again to explain what the problem was, but he was sure that magnetism was something that spurted out the end of the magnet only. 
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And e is just as cursed.
I wonder: Which is larger
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towr
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Re: Magnet Motor
« Reply #5 on: Jun 22nd, 2004, 1:01am » |
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Isolating the sides wouldn't help in that respect?
(Welcome back btw, where've you been?)
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Grimbal
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Re: Magnet Motor
« Reply #6 on: Jun 22nd, 2004, 11:38am » |
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As a matter of fact, I also thought of that design when I was young. But if I remember well, I thought of magnets attracting each other. Speak about reinventing the wheel!
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alien
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It is the matter for the physicist.
I can only remember that against magnetizing force there goes friction and gravitation, and eventually they win, and it is good bye to perpetual motor.
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towr
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Re: Magnet Motor
« Reply #8 on: Jun 22nd, 2004, 2:32pm » |
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But even without friction or gravity the wheel should stop (or never start in the firts place). So that can't be the problem.
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SWF
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Re: Magnet Motor
« Reply #9 on: Jun 23rd, 2004, 8:35pm » |
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With no losses such as friction, the wheel with no magnets will work just fine as a perpetual motion machine of the first kind. Why complicated it with magnets? With no losses, the magnet wheel will keep spinning too, but they are just another way waste energy (for example, by inducing current). As shown in the picture it looks like an unstable position, so it will at least move to about half way to the next magnet.
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Icarus
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Re: Magnet Motor
« Reply #10 on: Jul 19th, 2004, 8:07pm » |
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on Jun 22nd, 2004, 1:01am, towr wrote:| (Welcome back btw, where've you been?) |
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Things have been a bit unsettled this summer. I've had a lot of other distractions. I'll probably continue to be spotty until September. And when I have stopped in, I mostly have been trying to catch up, instead of coming up with new posts.
I guess this will give T&B the chance to take over 2nd place in the postings!
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"Pi goes on and on and on ...
And e is just as cursed.
I wonder: Which is larger
When their digits are reversed? " - Anonymous
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towr
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Re: Magnet Motor
« Reply #11 on: Jul 19th, 2004, 11:52pm » |
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on Jul 19th, 2004, 8:07pm, Icarus wrote:| I guess this will give T&B the chance to take over 2nd place in the postings! |
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Possibly, but he hasn't posted in nearly two weeks either.. And you've still got a good lead 
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