1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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


    User Avatar
    Science Advisor
    Homework Helper

    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


    User Avatar
    Homework Helper

    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.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook