1. Not finding help here? Sign up for a free 30min 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!

Fluid Question

  1. Sep 25, 2007 #1
    A cylindrical bucket, open at the top has height 27.0 cm and diameter 13.0 cm. A circular hole with a cross-sectional area 1.49 cm^2 is cut in the center of the bottom of the bucket. Water flows into the bucket from a tube above it at the rate of 2.28×10−4 m^3/s

    my work
    let 1 denote the top and 2 denote the bottom

    Q = V1A1
    V1 = Q/A = 0.01718 m/s

    Q = V2A2
    V2 = 0.01530 m/s

    using bernoulli's
    top bottom
    P + pgh + 1/2pv^2 = pgh + 1/2pv^2 + P
    P's are equal and cancels out
    rho's cancel out
    there's no pgh on bottom
    we are left with
    h = [ 1/2(v2)^2-1/2(v1)^2 ] /g

    the answer i get is 0.00179m which is 0.1179 cm but that's not the answer...can anyone see where i went wrong? thank you very much.
  2. jcsd
  3. Sep 25, 2007 #2


    User Avatar
    Homework Helper

    you're probably forgetting to convert something from cm to m or some such thing... I found

    h=0.11725 meters

    actually, only good to 2 sig fig?

    h=0.12 meters
  4. Sep 25, 2007 #3
    really? ? any idea what i converted wrong?
    did you get 0.01718m/s and 0.01530m/s for velocities? ... hm
  5. Sep 25, 2007 #4


    User Avatar
    Homework Helper

    no idea. sorry.

    I don't remember off hand, if I can find my scratch-paper I'll let you know.

    good luck.
  6. Sep 27, 2007 #5
    1cm^2 = .0001m^2 so 2.28x10^-4/1.49x10^-4 gives a velocity of 1.53m/s

    I just plugged it in to toricelli's equation (v1=sqrt(2g(h2-h1)) and solved for h2 (h1 is 0), which gave the answer .119m = 11.9cm.
  7. Sep 27, 2007 #6


    User Avatar
    Homework Helper

    that neglects the velocity of the water at the top of the bucket... valid if A_top >> A_bottom only.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Fluid Question
  1. Fluid Questions (Replies: 22)

  2. Fluids Question (Replies: 0)

  3. Fluids Question (Replies: 3)

  4. Fluid Question (Replies: 11)

  5. Fluid Question (Replies: 21)