Can Centripetal Force create Gravity?

  1. What i'm trying to get at is this, can a spinning framework of rings build enough centripetal force to keep a mass of liquid at the centre of the frame work? And if so what would be the relationship and conditions that would have to be met?
    Really need help:|
     
  2. jcsd
  3. mathman

    mathman 6,518
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    A spinning fluid would tend to go the outside, not toward the center. That is the principal of the centrifuge.
     
  4. well thank you mathman
     
  5. but i ment if the sphere was spinning and like a gas was in it, if most of the gas would travel towards the centre. Please advice
     
  6. Is that the whole notion behind artificial gravity in a spacecraft? A spinning spacecraft can reproduce the effects of gravity if I am not mistaken?
     
    Last edited: Jul 1, 2009
  7. Vanadium 50

    Vanadium 50 17,768
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    The gas will not go to the center. Why do you think it would?
     
  8. HallsofIvy

    HallsofIvy 40,544
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    NO, it wouldn't. It would travel toward the circumference. That was mathman's point.
     
  9. HallsofIvy

    HallsofIvy 40,544
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    People walking on the inside wall of the spinning space craft (heads pointed toward the axis of rotation) would feel a force pushing them against the space craft. Than can "simulate" gravity but will not be exactly the same. For example, in all but an immense space craft, coriolis forces would be evident.
     
  10. Chronos

    Chronos 9,989
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    A spinning fluid mass would resemble a galaxy in deep space. Gravity limits the effects of centripetal force.
     
  11. Wallace

    Wallace 1,253
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    I have no idea what you are trying to say? In a galaxy gravity is what provides the centripedal force that keeps it together??
     
  12. mathman

    mathman 6,518
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    In a galaxy the centripetal force is gravity.
     
  13. Wallace

    Wallace 1,253
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    Yes, that's what I said? At least that was what I intended to say....
     
  14. Yes...Theoreticaly this is possible. For simplisity sake take for example a ring and contain within it two elements... one a gas and other liquid. Let the gas be significantly "heavier" than the fluid. When spinning centripetal force would pull the heavy gas to the outside and leave the fluid (lightier) in the center...Is this even what you are asking???
     
    Last edited: Jul 9, 2009
  15. However, I don't know of any Gas heavier than liquid... so in accuality I dont think so
     
  16. So is the difference in behavior mainly due to the atomic freedom that exists in gasses

    Does this amount to saying that randomly circulating gas molecules cannot be bound by the centripetal force?

    How does gravity keep them together, is gravity stronger than centripetal force?
     
  17. Can you please explain in more depth what you are saying? What centripetal force are you refering to??
     
  18. Several levels of issues here:

    1) One is called 'miscibility' see: http://en.wikipedia.org/wiki/Miscibility

    2) Whether 'randomly circulating gas molecules' are 'bound' depends on their energy and strength of the forces involved.

    3) In this particular case, the substances appear to be already contained -- according to the original question. So this should not be an issue.

    4) Actually, in the case as presented -- a gas -- the presence of gravity or centripetal or any force is really unimportant. The gas is going to fill the volume.

    5) A liquid would only maintain being a liquid in the presence of additional gas (of some kind) filling any extra volume (or vaporize to expand to fill the volume)

    6) If the containing object (spaceship) is spinning, the denser material will settle against the outer 'walls'.
     
    Last edited: Jul 13, 2009
  19. Consider a box with some gas and a lot of holes(very hypothetically)

    Let us say i send the box into revolutions, now by what we have seen the gas would escape out of the holes, as the box rotates?

    Now however if the gas is gravitationally bound like it is for say jupiter, the gas does not escape, i mean why is this any different? Does this mean that gravity influences gas molecules differently than it is affected by centripetal force?
     
  20. Janus

    Janus 2,388
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    A centripetal force is one that acts toward the center, so gravity is a centripetal force.

    In your spinning box, the centripetal force is supplied by the walls of the box pushing inward on the gas preventing the molecules from following a straight line path as would be natural to them. When you put holes in the box, you have areas where there is no centripetal force to contain the gas and it escapes.
     
  21. D H

    Staff: Mentor

    Better: Gravity is a central force. Centripetal force is a kinematical rather than dynamical concept. This page, http://encyclopedia.stateuniversity.com/pages/3970/centripetal-force.html explains central versus centripetal versus centrifugal forces in a nice, simple manner.

    What centripetal force? You are acting as if centripetal force is something real in and of itself. It isn't. The real (i.e., physical) force in your rotating box is the electrostatic repulsion between the surface of the box and the gas molecules that hit it. The mass of the gas itself is insignificant. The real force in the case of Jupiter is the mass of all the stuff that comprises Jupiter. Compare this to the gas in a box situation. The gravitational force exerted by the gas on a gas particle near the surface of the box (or anywhere inside the box) is immeasurably small.
     
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