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Pressure vs. neck shortening of a balloon

  1. Oct 31, 2013 #1
    Pressure vs. "neck" shortening of a balloon

    I swear this is not a homework question :approve:

    The purpose of this question is to simulate the shortening of the cervix ("neck") as a result of the increase of pressure -> volume of the female womb.

    I would like to come up with a set of equations connecting between the:
    1. cervix ("neck") length - shown as 40mm and 25mm in pics
    2. overall thickness - shown as 15mm in pics
    3. womb radius - shown as 100mm and 105mm in pics (random approximate numbers)
    4. material properties (young's modulus, yield strength, density if relevant)

    We can assume the:
    a. Thickness stays approximately constant
    b. material properties stays constant

    So in theory I would be able to input the pressure inside the balloon and receive the cervix "neck" new length (shortening) as a result of the balloon inflating and taking away from that neck's length.

    I would love someone to guide me and send me the right way. I can't really use laplace's/pascal law because the thickness is not negligible.

    Thanks a lot!

    Pics for demonstration

  2. jcsd
  3. Oct 31, 2013 #2


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    Are we talking about people or balloons? Your post is confusing.
  4. Oct 31, 2013 #3
    Balloon is the analogy simplification of the human womb.
    Let's stick with balloons.
  5. Nov 1, 2013 #4


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    Sorry, don't see the similarity.
  6. Nov 1, 2013 #5
    http://www.shinesa.org.au/images/dmImage/SourceImage/Stages-of-pregancy.gif [Broken]
    Last edited by a moderator: May 6, 2017
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