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Questions about gravity

  1. Dec 16, 2009 #1
    Ok, I've been thinking alot of this lately.

    What are the components for a working gravitational force?

    Can several been needed to get a gravity at all in the beginning?

    Would the dens/cm3 of atoms around a planet(like earth) affect earths gravity? Or even been the one of the components needed to make gravity?

    When earth was hot it let of alot of steam and smoke(I think) it must have been a struggle of forces. Vakuum vs ?. Would extreme rotational force make something like steam follow the planet and thus making a counter-pressure against vakuum of space? If that would be true, can that be what keep us on the ground? I've been thinking of this because it takes alot of speed and energy just to go thru the soundbarrier. And that is in a horisontal direction. Thus the pressure down doesn't affect the plane as much as when an spacecraft goin upward.

    This is just a some of my thoughts.
    And here is a little clip from youtube I picked up some time ago(the reason why I'm here)

    ps: I'm not an expert on these kinda thing so I'll have a hard time explaining what I meen.
  2. jcsd
  3. Dec 17, 2009 #2


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    Welcome to Physics Forums.
    According to Newton's theory of gravitation, all that is needed is objects with mass .

    Not quite sure what you are asking. Do you mean was mass (the necessary component for gravity) necessary for there to be gravity at the time of the Big Bang? I'd say yes.

    It is the mass of the atoms that compose a planet that are necessary to have gravity.

    Well, there would have been more gas vapor when the Earth was molten, but that is really digressing away from the question of gravity.

    Hmmm. Again, completely different topic, unrelated to gravity.

    Hey, cool video! That is an example of what can happen in the absence of gravity. The ball of water is acting as a centrifuge, by the way.

    Not quite sure what you are trying to ask, is it just about gravity or something more? Wikipedia is often a good place to start:
  4. Dec 17, 2009 #3
    sorry if i'm overcautious but you are not speaking about gravity holding the sphere together, are you (that would be VERY weak and unable to hold it together - this is done by surface tension). The word microgravity refers to earth's gravity.
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