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Homework Help: Vector field

  1. Sep 16, 2008 #1
    1. The problem statement, all variables and given/known data

    A thin, circular plate assumed to lie on the xy-plane is rotating about its center, located
    at (0, 0), with angular speed ω. (ω > 0 means that the plate is rotating in the counterclockwise direction.) Show that the velocity field of of this plate is given by v(x, y) = −ωyi + ωxj.
    You must derive this result from an examination of the trajectories of points on the plate, and not

    2. Relevant equations
    v = ω × r

    3. The attempt at a solution
    based on the formula v = ω × r,” where ω = ωk is the angular velocity vector
    But, the prof said that i cant simplely write v = ω × r..
    ** hope someone would like to help me get the correct answer**
  2. jcsd
  3. Sep 16, 2008 #2
    You are using rectangular coordinates, not tangential-normal coordinates. I believe you need to better describe the "r" term.
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