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Train from New York to San Francisco using permanent magnets only?

  1. Sep 23, 2014 #1
    Never mind the title. It could be New York City to Newark. The idea is thus:

    Permanent Magnet Rail - Train


    Now imagine a train running on rails, and permanent magnets arranged on the side of the train, suitably arranged so as to cause forward motion of the train?

    I am not familiar with calculations involving magnetic forces, so maybe the cost of such an arrangement would be prohibitive given the cost of 'rare - earth' permanent magnets, and how many would be needed.

    And what about the effect of magnetic forces on passengers?

    Another Method- Suspended slightly off kilter magnetic suspension

    In fact, a method of suspending a train using permanent magnets only has been devised:

    http://www.21stcenturysciencetech.com/articles/magnetrain.html

    If the arrangement of magnets were slightly out of true, would it not result in a small force in either direction to push the train along?
     
  2. jcsd
  3. Sep 23, 2014 #2

    Borek

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    Those magnets are not for keeping the train in motion, they are there to make it levitate, so that there is no friction. Google for maglev trains.
     
  4. Sep 23, 2014 #3

    Bandersnatch

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    It would be prohibitive, but not in the way you think. The work done by magnets repelling each other will never be more than the work required to overcome the repulsion of the remaining length of the track. No matter how you arrange the magnets, sliding onto the next iteration of the magnet arrangement will always cause the train to slow down by the same amount(plus losses) as the previous would speed it up.
    What you're proposing is essentially the same as any of the many ideas of building a perpetuum mobile out of a clever arrangement of magnets. It won't work because of conservation of energy.
     
  5. Sep 23, 2014 #4
    But the permanent magnet railgun works - unless the science TV channell hoaxed the videos!

    Are you saying railguns made from permanent magnets do not work?
     
  6. Sep 23, 2014 #5

    Bandersnatch

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    Can you link to a description of what you mean by a "permanent magnet railgun"?
     
  7. Sep 23, 2014 #6

    A.T.

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    As has been explained to you in the locked thread, it merely converts potential energy into kinetic energy. But you have to put that potential energy into the train initially, so you can just as well use it to propel the train underway in a controlled manner.
     
  8. Sep 23, 2014 #7

    Borek

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    Staff: Mentor

    Thread closed.
     
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