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Friction force calculation of syringe plunger

  1. Jun 12, 2012 #1
    Hi all,

    This is my first post here. I finally decided to sign up after using the site for many years.

    I am working on a project involving a syringe mechanism. I am using a stock 6ml syringe. I'm trying to calculate the static friction of the rubber seal.

    I have measured both the pull and push forces required to move the plunger, but am blanking on how to actually get the coefficient of friction from those numbers.

    The pushing force is:0.625
    The pulling force is: 0.677777778

    Thank you for all the help!

  2. jcsd
  3. Jun 12, 2012 #2


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    Staff Emeritus
    Science Advisor

    I think you would have to know the force being applied to force the two surfaces together, not sliding back and forth over each other.
  4. Jun 12, 2012 #3
    Hm, okay. Any suggestions on the best way to go about that?

    Thank you
  5. Jun 12, 2012 #4
    I think i figured it out.

    After drawing out the free body diagram, I can use the actual forces i measured without having to solve for the coefficient of friction.

    Thank you for your help Drakkith
  6. Jun 12, 2012 #5


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    Staff: Mentor

    Why do you need the coefficient if you have the friction force?

    (edit: you figured it out while I was posting.)
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