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Stable levitation.

  1. Oct 4, 2006 #1
    For an experiment I need to achieve a stable axis of permanent levitation. Due to how magnets function I can't exactly go about this a simple way and my best bet is to probably go with a sort of eletromagnetism. I was thinking about buying one of those $80 floating globes, taking it appart and studying it... But those don't exactly seem to be what I'm looking for since they wobble around abit too much to be called stable for what I'm trying to pull off.

    Any ideas? (I apologeize if this is the wrong forum branch... there was so many :()
     
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  3. Oct 4, 2006 #2

    berkeman

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    How many electromagnets can you use? Like can you put them over and under and around the object? How big is the object, what is its shape, and what is it made of? Do you need to make a platform to levitate a general mass, or are you supposed to levitate the mass directly?
     
  4. Oct 4, 2006 #3
    The intinal mass is estimated at a 5-ish pound disc. I need the center "pinned" on a stable axis so it spins/rotates. I don't want to use super-conducitors or 'diamagnets'. If it will dislocate from it's axis with a simple bump then it's pointless and can be extremely dangerous because the disc will be spinning at a little around 2,000 RMP as a test to see if the levitation is stable enough to hold the actual prototype project.

    Edit- oh, and it isn't 'homework' or anything of sorts just a personal project/hobby. Trying to build a mini self-sustaining generator, for that I need to look for loopholes in the law of thermodynamics and address the oh-so-many flaws. I can use as many parts as I want. Right now the main idea is to get it working, levitate a disc on a stable axis.
     
    Last edited: Oct 4, 2006
  5. Oct 4, 2006 #4

    berkeman

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    Well, "self-sustaining generator" sounds a awful lot like perpetual motion machine. Hopefully you aren't wasting your time on that.

    I googled some of this stuff and came across Earnshaw's Theorem. Pretty interesting stuff.

    http://www.hfml.ru.nl/levitation-possible.html
     
  6. Oct 4, 2006 #5
    Yeah. I did read his theory (infact that exact site!) Though it just tells me the basics of it and i have no knowledge of how to build such thing to stablize levitation and no, it isn't a perpetual motion machine. Those things are pretty much impossible, however I have this theory that you can ampify energy. For an instance you give the generator maybe 100 volts input, and through a specific and controlled frictionless cycle it can end up giving out 200 volts JUST maybe.

    The laws of thermodynamics state that if you input any enery, any other that it exerts will get halved. I'm trying to find a way around it to actually boost it in a way well think of gear raitos in an eletrical sense. :S... I'm not really the type to explain things I have worked out in my head, though I'd apperecaite some help on how I'd levitate an object with a stable axis. Oh dear.. .I was ranting =x
     
  7. Oct 4, 2006 #6

    NoTime

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    Putting 100v in getting 200v out is trivial.
    You can buy a number of different solutions to this.
    Cheap! And no moving parts.

    Thing is that P=EI.
    P out will always be less than P in.
     
  8. Oct 4, 2006 #7

    berkeman

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    Hmmm. That's a different thermodynamics from the one I studied in undergrad. Do you have a web pointer to the source of that assertion?
     
  9. Oct 5, 2006 #8
    Oh, sorry. I'm ad-libbing how if you drop a basketball each time it bounces it is half the original height/energy that you inputted. It's the best way to explain why thermodynamics do not permit perpetual motion... imo.
     
  10. Oct 5, 2006 #9
    "If you drop a basketball each time it bounces it is half the original height/energy that you inputted"

    The height at which the ball bounces is determined by the air resistance and other forms off energy loss. Even if this was so it makes no sense to make the general claim:

    "The laws of thermodynamics state that if you input any enery, any other that it exerts will get halved"

    based on this individual case.

    If you are interested to see why 'perpetual motion' is disallowed by current physics try having a look at the first and second laws of thermodynamics.
     
    Last edited: Oct 5, 2006
  11. Oct 5, 2006 #10

    Mech_Engineer

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    I think the best way to describe why prepetual motion can't exist in thermodynaimc terms is entropy, but that's just me :tongue2:

    But if you drop a basketball it doesn't necessarily bounce half as high, it depends on its coefficient of restitution and can be very close to the same height in many cases. Basing your studies off of this "case study" is a bad idea... and relating a generator that "creates" energy to this case can't be a good idea anyway.

    Besides, this doesn't really have anything to do with thermodynamics... it is a physics/dynamics problem. Trying to find "loopholes" in thermodynamics will not get you very far anyway. It sounds to me like you are trying to create a generator, but if nothing is mechanically touching this "spinning disc" how will you impart mechanical work on it in the first place to generate electrical energy?

    I don't think your project will get very far, unfortunately... :uhh:

    I'd like to hear about these "oh-so-many flaws" in thermodynamics, by the way... :grumpy:

    ... and prepetual motion machines aren't "pretty much impossible," they ARE impossible.
     
    Last edited: Oct 5, 2006
  12. Oct 5, 2006 #11

    russ_watters

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    I'm not sure you understand the magnitude of the task you are undertaking: the world has generated perhaps a hundred million scientists and engineers since the 1st law of thermodynamics was thought up. Do you honestly believe you are smarter than all of them combined?

    We'll help you with bits of engineering and explain to you your misunderstandings of science, but please be aware that this is not a place to foster crackpottery. To that end:
    Wow. Your understanding of electricity is breathtakingly limited. Honestly, I think you'd be better off putting your project aside and starting off by learning how physics works before you decide you want to overturn it. Heck, how can you even know what you are trying to overturn?

    Voltage isn't power and it isn't energy (it is basically a force), so amplifying voltage is not a violation of thermodynamics. Have you heard of a device called a "transformer"...? It is the electrical equivalent of a block and tackle: a force multiplier.
    No, it says nothing of the sort. You'd be well advised to learn the laws of thermodynamics before deciding that you don't agree with them. :rolleyes: http://en.wikipedia.org/wiki/Laws_of_thermodynamics
    Also wrong. How high something bounces (jeez, haven't you ever actually bounced anything?) is determined primarily by the properties of the ball and the ground. Ie, some materials are more elastic and some more inelastic (coefficient of restitution, from above). If you've ever bounced a heavy rubber ball (such as a lacrosse ball) or a golf ball, you'll find it bounces to somewhere around 90% of the height it was dropped from. This experiment is often done in elementary school: http://pbskids.org/zoom/activities/sci/daredevilballjump.html

    Please understand: I'm not trying to insult you here, I'm trying to make you understand that you understand so little (almost shockingly little) about science that you need to start learning science and stop thinking you can invent science. You can't. I asked before if you think you are smarter than every scientist/engineer who ever lived. Let me assure you that you are not.
     
    Last edited: Oct 5, 2006
  13. Oct 5, 2006 #12

    LURCH

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    There's an interesting question. I don't see anything in your OP that prohibits physical contact with the disk, but that rule certainly seems implied. Rather than making assumptions, let me just ask; is it necessary that nothing be touching this disk? Otherwise, you could just put a pin through the center and keep it still that way.
     
  14. Oct 5, 2006 #13

    Mech_Engineer

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    His point of levitating the disc is to remove all chances for friction (although he has apparently forgotten about air)... I was pointing out that he hasn't thought enough about the project he is proposing... :grumpy: Why would he both impart mechanical work on the disc AND convert it to electricity using magnetic fields? The whole point that a generator has a mechanical shaft attached: it is the most direct way to impart mechanical work on it!

    I also find it incredible that he has no concept of electrical energy, yet he plans to design a system that "creates" it?!
     
    Last edited: Oct 5, 2006
  15. Oct 18, 2006 #14
    Here is a touchy setup:

    If the 5-ish pound disc can be a magnet then,
    align the mangetic field with the axis of rotation,
    use a platform beneath the rotating disc with a magnetic field perpendicular to the normal,
    point the disc's "north" pole to the "north" pole of the platform and spin the disc above the platform about an inch,

    If and only if the magnets are strong enough and the persession frequency is "right" the disc will leviate until the disc slows or the presession frequency changes out of the envelop.
     
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