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Homework Help: Calculating lift using bernoulli's equation

  1. Oct 25, 2009 #1
    1. The problem statement, all variables and given/known data

    What is the lift (in newtons) due to Bernoulli's principle on a wing of area....m^2 if the air passes over the top and bottom surfaces at speeds of ...m/sand ...m/s, respectively? I've given the values but I just want to know if I'm doing the problem right conceptually.

    2. Relevant equations

    P1 + 1/2rv1^2= P2 + 1/2 r v2^2

    3. The attempt at a solution

    Hello, can someone help me with the approach to this problem?
    I tried solving for P2-P1 in Bernoulli's and then using that as P in F=P/A and solving for F. I realize that the pressure on the bottom has to be greater than the pressure on the top to create lift so thats why I did P2-P1.
  2. jcsd
  3. Oct 25, 2009 #2

    Chi Meson

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    Science Advisor
    Homework Helper

    Yes, you are going about solving the problem correctly. It doesn't really matter whether you subtract P2 from P1 or vise versa. You just need the difference in pressure to find the "bernoulli force" and then you just say "it's upward."

    By the way, just do the problem as they ask you, and then let yourself know that the "Bernoulli force" is way over-hyped, and does not account for any more than 6% of total lift force on an airplane.
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