1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Magnetic train

  1. Dec 19, 2015 #1
    Hello
    I hope you know the phenomenon called "Magnetic train". My teacher used it in classes to demontrate electromagnetic phenomena. So he told the advanced learners (however, here I am xD) to investigate it, especially the forces and how certain parameters affect the velocity. But I do not understand at all how there can be a velocity with a force? and which forces appear? I hope you can give me at least a thought-provoking impulse.

    thanks a lot

    Ray

    upload_2015-12-20_20-21-53-jpeg.93542.jpg
    Image added by mfb to clarify which type of train is meant (see page 2)
     
    Last edited by a moderator: Dec 20, 2015
  2. jcsd
  3. Dec 19, 2015 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    How do you mean that question?
    A force can change velocity.
    Descriptions of the train concepts discuss that.
     
  4. Dec 20, 2015 #3
    yes but there seems to be a constant velocity and i wonder how this can be. woundn´t it be changing all the time?
     
  5. Dec 20, 2015 #4
    Due to inertia, something with no net force will maintain a constant velocity. A magnent suspending a train can precisely counteract the force of gravity, allowing the train to move at a constant velocity because the sum of forces is zero (they act in opposite directions). I think you might be asking something deeper than that, though, I'm not sure.
     
  6. Dec 20, 2015 #5
    very interesting, thank you! i agree but how does a magnet counteract the force of gravity when they are perpendicular to each other?

    i think there is only the force of attraction and the force of repelling. and the force caused by friction that opposes these two other forces. And gravity.
     
  7. Dec 20, 2015 #6

    NascentOxygen

    User Avatar

    Staff: Mentor

    It may be called a "magnetic train" but the magnets are not used to attach each carriage to the next one; the main function of the magnetic field is to raise the train off the tracks....to give a small clearance.
     
  8. Dec 20, 2015 #7
    that´s not what i meant, my experiment refers to a battery in a solenoid where there are magnets attached on each side of the battery. if you put it into, it´ll start to move.
     
  9. Dec 20, 2015 #8
    I think the OP is referring to this particular experimental demonstration, where the "train" is a battery with magnets attached to its ends, travelling through a wound copper wire "track".
     
  10. Dec 20, 2015 #9
    yes that´s right
     
  11. Dec 20, 2015 #10
    My instinct would be that this is due to the back-emf that arises from electromagnetic induction effects...though I'm not that sure...imhomogenous magnetic fields are always tricky to analyse
     
  12. Dec 20, 2015 #11
    so it is possible that it gains speed due to the back-EMF and than move till the battery is empty because of the forces.?
     
  13. Dec 20, 2015 #12

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    It does not, and there is no need to. The train is supported from below by the coil.
    It is useful to analyze horizontal and vertical forces separately.
     
  14. Dec 20, 2015 #13
    hmm i just thought there are only horizontal forces because of the friction
     
  15. Dec 20, 2015 #14

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Well, there is certainly a vertical force from gravity, and something balancing it (so the train doesn't fall through the table). Otherwise the train would float, and there would be no (horizontal) friction either.
     
  16. Dec 20, 2015 #15
    of course, but theforce from gravity is only important for the friction and the normal force neutralize it. right?
     
  17. Dec 20, 2015 #16

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    Right.
     
  18. Dec 20, 2015 #17

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    How a maglev train works..

    https://www.quora.com/How-magnetic-levitation-train-works [Broken]
     
    Last edited by a moderator: May 7, 2017
  19. Dec 20, 2015 #18

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    This is not the type of train discussed here.
     
    Last edited by a moderator: May 7, 2017
  20. Dec 20, 2015 #19
    mathewmical, I think you should edit your first post to include a picture of that particular experimental demonstration you're referring to, because "magnetic train" immediately causes most people to think about maglev trains =p
     
  21. Dec 20, 2015 #20
    okay i´ll do so :D
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Magnetic train
  1. A Train (Replies: 2)

  2. Train motion (Replies: 9)

  3. Train Problem (Replies: 3)

  4. Trains Problem (Replies: 6)

Loading...