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Homework Help: Water flow speed through a pipe

  1. Nov 8, 2011 #1
    1. The problem statement, all variables and given/known data

    Water flows through a 1.3 cm diameter pipe into a 295 L bathtub, which it fills in 5 min.

    What is the speed of the water in the pipe?
    2. Relevant equations

    V_in=v_L*t*A_L (Equation I got in my class lecture, I think its a variation of bernoulli's.)

    3. The attempt at a solution

    Solved for v_L in that equation, but thats not correct.
  2. jcsd
  3. Nov 9, 2011 #2


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    Did you check your units? You are given liters, cm, and minutes. What units are used for velocity?
  4. Nov 9, 2011 #3
    Clearly, the speed of the water in the pipe was
    [tex]\frac{295\ \ell}{5\ min} = 59\ \ell/min[/tex]

    But, I'm guessing you're looking for linear speed, not volumetric speed? (something along the line of 5 cm/sec, for instance).
  5. Nov 9, 2011 #4
    Actually 59 l/min is the volumetric flow rate which will equal velocity * cross sectional area of pipe. To make the units turn out correctly you will need to convert liters to cubic meters
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