   Hypothetical situation (regarding a kind of perpetuum mobile)
  I have a very weak background in physics, so I won't claim to know how much I'm fantasizing on this, so that's a fair warning. The question is - how would the following system behave:In total vacuum, a number (let's say 30 - or maybe 1500?) polarized magnets have been arranged in a perfect (let's just ignore this for now) circle. All of the magnets apply a pull on the "previous" magnet while being pulled by the next one. Will the circle of magnets start to rotate? If so, then how fast can/will it rotate (and depending on what)?Hypothetical application as an energy source (this is Roswell-style flight of fantasy): we arrange the magnets in a donut-shaped chamber (I believe these are called tokomaks) and fill the chamber with some gas to apply friction to the magnet ring to control the speed that they're rotating at. The less gas we have in the chamber, the faster the ring of magnets revolves, generating a magnetic field, which is then converted into energy by some methoid that could resemble electron excitation (I have no idea if there's such a thing - but I magine that should be possible to generate electricity).I know there are reasons why this is either not possible or just won't work - I'm just too stupid to know what those reasons are. But being a self-proclaimed philosopher/physicist with no proper background can sometimes lead to ideas that start to haunt you. This is one of those ideas :).[Edited by - irreversible on June 3, 2006 9:05:12 AM]
  I have absolutly no idea if they would start rotating or not, but my guess would be no. If the magnets are exerting influence on the next magnet equal to the influence being exerted on itself from the previous magnet then all magnets would remain stationary - wouldn't they? Like I said, IANAP (I am not a physicist).   ;Quote:Original post by SticksandStonesI have absolutly no idea if they would start rotating or not, but my guess would be no. If the magnets are exerting influence on the next magnet equal to the influence being exerted on itself from the previous magnet then all magnets would remain stationary - wouldn't they? indeed.to put it short: action is -reaction.without external forces, your magnets will remain happily where they are.   ;  I'll stress a very important point that I think you guys missed:/.../"a number polarized magnets have"/.../I'll also fix the OP.The thing is - if you can effectively pull an object to a magnet in Earth atmosphere, then is vacuum when the forces exerted on the previous magnet would surely be much greater, wouldn't they?Upon further consideration, the magnets could be bipolarized with that end, which is being pulled being considerably weaker than the pulling end (meaning that the next magnet pulls the previous one forward with considerably geater force than the previous one would pull the next one back).   ;  I'd use electro magnets instead. By controlling the current, you could control the amount of magnetism, and thus speed of rotation. The real question is: does it take more electricity to rotate the magnetic donut then the electricity that it generates?You could also build some sort of mechanical or electrical timer to pulse the electricity into the electro magnets so that they don't get stuck in between a push cycle.There was a report of a japanese inventor who built something like this in his garage and powered up about 30 light bulbs in a parallel circuit (or maybe it was serial).The two other questions are:-How much torque can you generate?-How fast can this spin?   ;Quote:Original post by slayeminI'd use electro magnets instead. By controlling the current, you could control the amount of magnetism, and thus speed of rotation. The real question is: does it take more electricity to rotate the magnetic donut then the electricity that it generates?You could also build some sort of mechanical or electrical timer to pulse the electricity into the electro magnets so that they don't get stuck in between a push cycle.There was a report of a japanese inventor who built something like this in his garage and powered up about 30 light bulbs in a parallel circuit (or maybe it was serial).The two other questions are:-How much torque can you generate?-How fast can this spin?That's what I find puzzling - magnetism (as is gravity) is a phenomenon that isn't understood at all well, which implies that potentially insane amounts of energy could be tapped into by utilizing these forces. The cool thing about magnets is that AFAIK (well, from personal experience), a magnet can pull far beyond its own mass (including up, resisting the earth's gravitational field within the atmosphere) by using nothing but its own magnetic pull (that is - it can lift itself). This is the important bit that I do not understand:Presuming this, I fail to see what would stop the above-described ring of magnets (electro- or otherwise) from spinning itself infinitely faster and faster, eventually reaching the speed of light. I know there's got to be a simple explantion (along the lines of division by zero :) ) - I just can't see it.   ;  I'll stress a very important point that I think you have missed:action = -reaction.   ;Quote:Original post by EelcoI'll stress a very important point that I think you have missed:action = -reaction.Okay - sorry for being stupid: to me that's a self-reference. Can you link this to the context?   ;Quote:Original post by irreversibleQuote:Original post by EelcoI'll stress a very important point that I think you have missed:action = -reaction.Okay - sorry for being stupid: to me that's a self-reference. Can you link this to the context?ask yourself this question: can you show me a net force on your asssembly of magnets? (no net force means no acceleration)hint: action = -reaction says you cant.   ;  A magnet does not simply attract something to it. It is itself attracted to the object with equal force. Tiny Iron filings jump to a large magnet only because the force required to move them is less than that needed to move the larger magnet. If you have two equal magnets then both would move and meet in the centre.Assuming your magnets A, B, C, D and E are in a circle A does not simply pull B towards it and B pull C towards it and so on. A and B are attracted toward each other with equal force, B and C towards each other with equal force (thus the forces applied to B in each direction are equal and it does not move), C is attracted to B and D equally, D to C and E equally, E to D and A thus closing the circle. So, all around the circle forces pulling each magnet either one way or the other are balanced so none of them move. You would have to apply external force to the magnets to move them which would cost energy.   