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Pressure difference in a horizontal constant area pipe

  1. Nov 18, 2012 #1
    1. The problem statement, all variables and given/known data

    see attachment

    2. Relevant equations
    not sure if these are applicable because i dont think its steady state anymore
    mass flow in=mass flow out
    sum of forces in x direction= rate of momentum in-rate of momentum out
    bernoulli's p+0.5ρ(v^2)= constant

    3. The attempt at a solution
    2.2a No
    2.2b true, true, false as bernoullis assumption states inviscid flow, true if the given equations are true, true as the fluid is slowing down so resultant force is going in the left so pressure force at 2 is greater then pressure 1.
    I am confused on making the correct assumptions could someone help me please?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     

    Attached Files:

  2. jcsd
  3. Nov 18, 2012 #2
    2B is false. The amount of liquid entering the pipe has to be equal to the amount of liquid exiting it in steady operation. Friction won't cause a decrease in velocity (at the wall the liquid isn't moving anyway for viscous fluids). The friction will cause a head loss though. So you see the impact in a decrease in pressure This energy is converted into heat. Maybe now you can get the other parts as well?
     
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