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Homework Help: Fluids bernoulli's equation problem

  1. Nov 13, 2006 #1
    Water flows throgh a horizontal tube of diameter 2.8cm that is joined to a second horizontal tube of diameter 1.6cm. the pressure difference between the tubes is 7.5kPa. which tube has the higher pressure flow? which tube has the higher speed flow? find the speed of flow in the first tube.

    P2=p1+ (1/2)density(rho)(v1^2-v2^2)

    how can i solve with out a velocity 1 or 2?
  2. jcsd
  3. Nov 13, 2006 #2
    Without worrying about numbers (quantitative parts) -- can you first answer the qualitative parts?
  4. Nov 13, 2006 #3
    pressure is greater in the bigger area with less fluid speed. the greater fluid speed has the least pressure.
  5. Nov 13, 2006 #4
    Okay -- now say you KNOW the pressure in each part -- just call them dummy variables say P_b and P_s for the big and small diameter tubes. Can you then individually know the speeds in the tubes as functions of P_b and P_s? then you know the difference between P_b and P_s. Try setting up those... Then you might have as many equations as unknowns ands be able to solve for all your unknowns, including the velocity you want.
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