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Homework Help: Gravitational potential

  1. Dec 26, 2008 #1
    The image below shows a sketh of gravitation potential (y axis) vs. position:

    http://img175.imageshack.us/img175/5717/60413547vb3.th.jpg [Broken]

    Can someone please explain why the potential does not equal zero at the neutral point - wouldnt the two potentials cancel each other out?

    Thanks
     
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Dec 26, 2008 #2

    D H

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    First off, why would you expect it to go to zero? That plot is of

    [tex]u(r) = -\left(\frac{GM_e}{|r|} + \frac{GM_m}{|R_m-r|}\right)[/tex]

    That function is negative definite: its value is negative for all finite values of r.


    Secondly, what do you mean by "neutral point"? This term has multiple meanings.
     
  4. Dec 26, 2008 #3

    tiny-tim

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    Hi nokia8650! :smile:

    Where is the potential being measured from (in other words, where is zero potential)?

    Potential is often measured "from infinity" …

    in that case, the potential will only be zero at an infinite distance from both the Earth and the Moon. :smile:
     
    Last edited by a moderator: May 3, 2017
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