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Potential Energy

  1. Apr 10, 2010 #1
    A very basic question:

    Why is the definition of gravitational potential energy, bringing an object from infinity (or any point of reference) to zero, the negative of the line integral of F.dr ? I am assuming since potential energy in an attractive field , which is defined to be negative, the integral was fixed to lead to this result... or is there a more mathematical reason?
     
  2. jcsd
  3. Apr 10, 2010 #2

    tiny-tim

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    Hi ian2012! :smile:

    potential energy (gravitational electric or whatever) is defined as minus the work done …

    and work done = integral of force "dot" displacement …

    so PE = -W = -∫ F.dr :wink:

    (and it has to be minus so that the work-energy theorem works)
     
  4. Apr 11, 2010 #3
    thank you for your post
     
  5. Apr 11, 2010 #4

    rcgldr

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    In the case of gravity from a point source, potential energy = -G m M / r. Because of this, using infinity as a reference point makes since, becaue - G m M / ∞ = 0, and all GPE's at finite distances from a gravitational point source would be negative.
     
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