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Homework Help: Quick error propagation problem

  1. Nov 16, 2008 #1
    1. The problem statement, all variables and given/known data
    we are trying to find the x -component of a velocity vector (V*cos[tex]\theta[/tex])
    our uncertainty for the velocity is +-.0003 and for the and it is .5(in degrees)
    how do we propagate the error for this
    v=.048 while [tex]\theta[/tex] =27 degrees

    2. Relevant equations

    3. The attempt at a solution
    using partial derivatives :
    (vSin[tex]\theta[/tex]).5 (degrees)+ (cos[tex]\theta[/tex]).0003=
    the problem is this is a really big uncertainti compared to the answer and i was just wondering whether i did this right?
  2. jcsd
  3. Nov 16, 2008 #2


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    Homework Helper
    Gold Member

    The method looks fine except that you need to convert your error to radians, as the relation [tex]\frac{d}{d \theta} \cos \theta=- \sin \theta[/tex] is only true when [itex]\theta[/itex] is in radians.
  4. Nov 16, 2008 #3
    thanks allot!!!:smile:
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