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Homework Help: Gravitational Potential

  1. Nov 9, 2009 #1
    Hi, I did a quick search but didnt find anything relevant so I apologise if this has been covered.

    My A2 Physics book says the following:

    My question is, the book does not go into any more detail and i am unsure what this equation is ment to actually be. I think it means G but i am unsure.

    Appreciate any help.
  2. jcsd
  3. Nov 9, 2009 #2


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    Welcome to PF!

    Hi Joe09! Welcome to PF! :smile:

    There's a slightly confusing difference between potential and potential energy …

    electric potential is potential energy per charge, and gravitational potential is potential energy per mass …

    that's why they divided Epotential by m. :wink:

    Gravitational potential (in a uniform gravitational field) is U = gh.

    (and btw I think we normally use U rather than V for potential)
  4. Nov 10, 2009 #3
    Thankyou for the welcome.

    Of course how silly of me!

    The equation:

    Epotential = Etotal - Ekinetic

    is equivalent to:

    GMm/R = mc2 - 1/2 mv2

    So when the physics book divides the equation by m we arrive at:

    GM/R = c2 - 1/2 v2

    which is equivalent to:

    Vgrav = constant - 1/2 v2

    I tell ya, working with integrals all day confudles the mind :blushing:

    U? Oh ok, it be nice if the worlds scientists/exam boards/teaching curriculums could agree on a universal symbol. Unless its only the UK which uses V :rolleyes:
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