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Infinite Compressibility

  1. Jan 27, 2012 #1
    Correct me if I am wrong, but I think that compressibility, generally tells how difficult it is to compress an object. Meaning, the higher the compressibility, the easier it will be to compress an object with a given pressure.

    I was asked in my University to describe an system of infinite compressibility.
    I think that would mean that the volume changes would be infinite with the exercise of least pressure. Does a system like that exists? I couldn't think of anything.
  2. jcsd
  3. Jan 27, 2012 #2
    2 things straight off the top of my head,

    Black holes "theoretically" compress matter into a space of zero volume so you could say the compressibility is infinite in that system.

    Ideal gases would also be infinitely compressible due their particles lack of volume. Though there is no ideal gas in real life.

    So no real physical systems but those might help you a bit.
  4. Jan 27, 2012 #3


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    I don't know. Is that what infinite compressibility means? That one would not have to provide work to compress the substance? Gases are highly compressible but work is needed to compress. If you do not have to supply energy to the system as work, then the temperature would not increase? If you heated the system, what would the effect be then -would the pressure increase? Is the system entropy a constant? Can one consider space itself an infinite compressible system?

    Just thought I would list some of the things your University might ask you, and you should have the answers to in your description of an infinite compressible system, and you are not left with a "umm uhh well uhh " answer.
  5. Jan 28, 2012 #4
    Well I found the answer today.
    The answer from rollcast was wrong as I thought. He was talking about infinite density, not compressibility. Compressibility is the change of density with pressure, not the value of density.
    In phase transitions, a system has infinite compressibility, because the changes in desinty are huge, while pressure remains stable. So partly, an ideal gas can be a system with infinite compressibility.
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