1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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: Solids and Fluids: Time

  1. Apr 11, 2010 #1
    1. The problem statement, all variables and given/known data

    SAE no. 10 oil has a viscosity of 0.2 Pa· s. How long (in sec) would it take to pour 4 liters of oil through a funnel with a neck 10 cm long and 2.9 cm in diameter. Assume that it is poured in such a way that the oil level is kept just above the top of the tube.

    Hint: The specific gravity (= ratio of its density to that of water) of the oil is 0.70.

    3. The attempt at a solution

    Dp = rgL
    = (700 kg/m3)*(9.8 m/s2)*(10*0.01 m) = 686
    The fow rate is given by Poiseuille's law:
    Q = p r4 Dp / (8 h L)

    => t = V / Q = 8 V h L / (p r4 Dp) = 8*(4*10^-3)*0.2*(10*0.01) / (700*(0.5*2.9*0.01)^4*686 = 0.03 s = wrong answer.

    Please advise! Thanks!
  2. jcsd
  3. Apr 12, 2010 #2
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook