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Homework Help: Maxwell's wheel question

  1. May 13, 2015 #1
    Well, I have to do experiment with Maxwell's wheel, but i struggle with theoretical background.
    If you dont know what Maxwell's wheel is,

    I understand conservation of energy and how we made that equation, but this part i dont get;

    Ok, i understand derivative, but how do i get s(t) and v(t).
  2. jcsd
  3. May 13, 2015 #2

    Doc Al

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    Staff: Mentor

    You just need a bit of algebra. Hint: first solve for the acceleration.
  4. May 13, 2015 #3

    rude man

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    Homework Helper
    Gold Member

    You have a very simple ODE. Solve it for v(t) using the given I.C. for v, then solve for s(t) = ∫v(t)dt using the I.C. for s.

    EDIT: go with Doc Al, don't need formal ODE approach. Divide by v and solve for accel.
    Last edited: May 13, 2015
  5. May 14, 2015 #4
    I see that v derivated is acceleration, so when i divide equation and kill v(t) i get acceleration,
    a= mg/(m+I/r2)

    should i just double integrate it now for s(t) and once for v(t), yes,i get it.
    Last edited: May 14, 2015
  6. May 14, 2015 #5
    One more thing
    http://www.officeplayground.com/Assets/ProductPreview/pi3600-3799/3653_maxwellswheel_1.jpg [Broken]
    In scheme of wheel, where does ds point to?
    Last edited by a moderator: May 7, 2017
  7. May 14, 2015 #6

    Doc Al

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    Staff: Mentor


    Sure. (Or, since the acceleration is constant, you can use the standard kinematic formulas.)

  8. May 14, 2015 #7
    Alright. I cant remember why, if ds=d(phi)xr, where x i vector cross multiply. Using right hand rule, it should be perpenicular towards angle and radiaii?
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