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Homework Help: Question regarding flow rate

  1. Feb 8, 2010 #1
    1. The problem statement, all variables and given/known data
    An alcohol flows smoothly through a horizontal pipe that tapers in cross-sectional area from A1 = 43.7 cm2 to A2= A1/4. The pressure difference Δp between the wide and the narrow sections of the pipe is 8.8 kPa. What is the volume flow rate ΔV/Δt of the alcohol? The density of the alcohol is ρ = 796 kg/m3.

    2. Relevant equations
    I figured I would have to use:

    v1 = sqrt( 2*deltap / 15(rho) )

    3. The attempt at a solution

    I'm not entirely sure how to start this. I'm very cinfused.

  2. jcsd
  3. Feb 9, 2010 #2


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    Homework Helper

    Hi 12342, welcome to PF.
    The relevant equations are
    P1 +1/2*ρ*v1^2 = P1 + 1/2*ρ*v2^2 ......(1)
    And rat of flow
    Q = A1*v1 = A2*v2........(2)
    From the second equation find v2 in terms of v1 and put it in eq. 1. Then solve for v1and then Q.
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