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Magnetic Rotation

  1. Jul 4, 2015 #1
    If I have a magnetic setup in frictionless, etc. area as follows:


    Will the "south" pole rotate up to the "north" pole, causing the system as a whole to rotate?
  2. jcsd
  3. Jul 4, 2015 #2


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    Why not the other way around?
  4. Jul 4, 2015 #3
    It is my understanding (and it has been awhile since magnetics in college) that it would rotate toward "north" - like a compass. But for sure I would like to be able to control the direction of rotation...
  5. Jul 4, 2015 #4


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    Are the vertical and horizontal bars free to rotate relative to each other, like the compass needle can rotate relative the Earth? If, yes do they have the same mass ratio as the a compass needle and the Earth?
  6. Jul 4, 2015 #5
    It is all connected. Ultimately, it is a full cross shape that I am trying to rotate about the center.
  7. Jul 5, 2015 #6
    This is operating in a frictionless environment. Each bar is the same mass, and like I said there are four making a complete cross. I am trying to see if the whole thing will start rotating about the center as the "south pole" is attracted to the "north pole".
  8. Jul 5, 2015 #7


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    So you've effectively taken two bar magnets and put on on top of the other, offsetting one by 90 degrees?
  9. Jul 5, 2015 #8


    Staff: Mentor

    No. An internal force cannot cause a net torque.

    We don't discuss perpetual motion machines here. Thread closed.
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