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Homework Help: Conservation of forces and poetential energy

  1. May 5, 2008 #1
    conservation of forces and poetential energy!!!

    1. The problem statement, all variables and given/known data
    a potential energy function for a 2d force is of the form U=3x^3y-7x. find the force that acts at the piont (x,y).


    2. Relevant equations

    U=3x^3y-7x

    3. The attempt at a solution

    how do i do this? tahe the derivative?
     
  2. jcsd
  3. May 5, 2008 #2
    Yes. You might want to reread what your textbook says about the gradient of the potential energy function.
     
  4. May 6, 2008 #3
    ok so i took the derivatives with respect to x and y
    d/dx=9x^2y-7 and d/dy=3x^3
    what do i do now? Subtract then, this chapter in my book dosen't talk about the gradient.
     
  5. May 6, 2008 #4
    The gradient is the vector idU/dx + jdU/dy (in two dimensions)
    see also http://en.wikipedia.org/wiki/Gradient" [Broken]
     
    Last edited by a moderator: May 3, 2017
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