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Homework Help: Viscosity of Water

  1. Jan 20, 2007 #1
    1. The problem statement, all variables and given/known data

    Hi guys, I need to find the flow of water at temperature of 350K. I had to do this, but for air in the same problem...but I can't find an equation to account for the viscosity change, due to temperature rise. My book lists it at 86.0 x 10^-5 Pa*s @ temp 300K.

    2. Relevant equations

    3. The attempt at a solution

    I've searched the web for some time now, and can't find any equations for water. Any help would be great.

  2. jcsd
  3. Jan 20, 2007 #2


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    Google for "viscosity water temperature".
  4. Jan 20, 2007 #3
    Ok, so I found the page(thanks)....and the first link takes me right to what I need. But....the viscosity is dynamic(is that the same as just plain viscosity?).......and also, they have it measured in kg/m*s and I need it measured in Pa*s. Again, I've looked in my book and on the net, and I can't find out how you convert between those two.

    The only conversion that I found(and I don't think it works)...but its 1kg(force)/m^2 = 9.806650 Pa.
  5. Jan 20, 2007 #4
    Does anyone know about these conversions.....???
  6. Jan 21, 2007 #5


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    1 Pascal (Pa) is 1 Newton/m^2

    1 Newton (N) is the force to accelerate 1 Kg at 1 m/s^2

    So 1 Pa.s = 1 N.s/m^2 = 1 (Kg.m/s^2).(s/m^2) = 1 Kg/(m.s)

    BTW There are two different units for viscosity, dynamic and kinematic. Kinematic viscosity = dynamic viscosity / density. The one you want is dynamic viscosity.
  7. Jan 21, 2007 #6
    Oh ok.....so they are the same units then(or equivilant)....I guess I didn't put to much time into it, seems pretty obvious now, duh. ha. Well thanks though, I really appreciate you showing me the right direction!
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