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Confused about uniform circular motion (and it's velocity vector)

  1. Feb 18, 2010 #1
    Sorry if this is the wrong (sub)forum!

    I need some help to understand how to express the following:

    The velocity vector

    When this is given:


    Both in magnitudes. I want to obtain an expression for the velocity vector when the angle theta (radians/s) is changed. That is, when i know the position of the particle:

    (x,y) = r*(cos(theta),sin(theta)) Note: center is at (0,0)

    I know the velocity vector is tangent to the point on the circle at any given time, and that it can be determined via the cross-product between the vectors omega and r, that is:

    V = Omega X r

    But how do i convert from magnitudes to vector form?? - it's very simple, i'm sure of it, but i cannot see anything in my book in calculus...

    Any help appreciated - i hope i made myself clear
  2. jcsd
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