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From where comes Gravity energy?

  1. Jul 26, 2009 #1

    first I'm glad having found this very interesting forum.
    Initially I hesitated before asking my question, because its answer is probably obvious for the specialist. But my physics studies were a long time ago, and I must say the gravity related issues are being confused in my brain.

    The question that came to mind after reading other interesting posts:
    Due to curved space-time (as they say) an object will visually fall towards the center of a massive object nearby (typically my iPhone towards the wooden floor on Earth [not broken]).
    From where comes the energy that moves the object? Is there some consumption somewhere? Is it just a matter of fact due to the Universe rules?
    Meaning, if nothing would change on Earth/Universe, the same force would be applied to objects without reduction infinitely?

  2. jcsd
  3. Jul 26, 2009 #2

    Jonathan Scott

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    Gold Member

    In both Newtonian theory and relativity, the energy of an object falling in a static gravitational field is constant. An object which is in a higher potential has "potential energy" due to that position. When it is freely falling (where that term includes orbits and being thrown upwards), the potential energy can be converted to or from kinetic energy, but the total is constant.
  4. Jul 26, 2009 #3
    I do not understand your last sentence...but if you are also thinking about force, then work IS done as an object moves in a gravitational field.

    Gravitational potential energy is taken as zero at infinite distance from the center of attraction and the difference in potential energy at two points is the work done in moving a body from one point to another.

    This is consistent with post #2.
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