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Definition of viscosity

  1. Dec 22, 2009 #1
    In a question,I found a unit call 'viscosity',but i don't what it is
    can anyone explain the definition,I have no idea of this completely,THX
  2. jcsd
  3. Dec 22, 2009 #2


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    Welcome to PF!

    Hi SOHAWONG! Welcome to PF! :wink:

    Solids have friction.

    Fluids (liquids and gases) have viscosity.

    Both measure the resistance to movement.

    The main difference between friction and viscosity is that when an object moves against a solid, the solid stays where it is, but when an object moves through a fluid, some of the fluid moves with the object.

    See http://en.wikipedia.org/wiki/Viscosity" [Broken] for details. :smile:
    Last edited by a moderator: May 4, 2017
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