Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Find Viscosity

  1. Nov 13, 2008 #1
    1. The problem statement, all variables and given/known data
    Find the viscosity of water given that;

    flow rate ([tex]cm^3 s^{-1}[/tex]) = 2.0
    height from tube (m) = 0.1

    l (m) = 0.2
    r (mm) = 1
    [tex]\rho[/tex] = 1000
    g = 9.81

    Using the equations;

    x = [tex]\frac{Flow Rate}{Height}[/tex]

    x = [tex]\frac{\pi \rho gr^4}{8l\eta}[/tex]

    3. The attempt at a solution

    Okay so first, and the most important bit I don't know if I'm doing right I convert the flow rate from [tex]cm^3 s^{-1}[/tex] to [tex]m^3 s^{-1}[/tex] by multiplying by [tex]10^{-6}[/tex]

    So flow rate is now [tex]2 * 10^{-6} m^3 s^{-1}[/tex] ***I don't know if that bit is correct.***

    Then x = [tex]\frac{2 * 10^{-6}}{0.1} = 2 * 10^{-5}[/tex]

    and [tex]2 * 10^{-5} = \frac{\pi \rho gr^4}{8l\eta}[/tex]

    After re-arranging and substituting I get;

    [tex]\eta = 9.6*10^{-4}[/tex]


    If anyone could check my answer it would be greatly appreciated I haven't done physics for so long I've pretty much forgotten everything.

    Thanks in advance :smile:
  2. jcsd
  3. Nov 13, 2008 #2
    I got the exact same answer you got, using your data.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook