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Homework Help: Finding the circulation of a vector field

  1. Feb 14, 2014 #1
    1. The problem statement, all variables and given/known data
    Can someone guide me through solving a problem involving the circulation of a vector field?
    The question is as stated
    for the vector field [itex] E = (xy)X^ - (x^2 + 2y^2)Y^ [/itex], where the letters next to the parenthesis with the hat mean they x y vector component. I need to find the circulation of that vector field given by the close path of a triangle going from (0,0) to (0,1) to (1,1) and back to (0,0)

    2. Relevant equations

    circulation = ∫Bdl

    3. The attempt at a solution

    I tried taking the partial derivatives with respect to x and y and then added the results. Then I took the double integral from 0 to 1 for the given result. The answer in the back of the book says -1. The only examples I see everywhere is the one with the circle which is very simple and only has one path. I understand I can add the integration of the individual paths, so how can I do the last part goinf from (1,1) to (0,0) when the vector changes for both variables?
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 14, 2014 #2


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    Science Advisor
    Homework Helper
    Gold Member

    You need to show your work. Among other possible errors, integrating both x and y from 0 to 1 would describe a square, not a triangle. Are you using Green's theorem? That would give an integrand of ##Q_x - P_y## not their sum.
  4. Feb 18, 2014 #3
    Thank you for your reply. I didn't know what I was doing, but I used Green's theorem as you said and helped me solve the problem. I integrated with respect to x from 0 to 1 and with respect to y from 0 to x and I obtained the right answer.
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