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Homework Help: Bernoullis principle and lift on a wing of plane

  1. Apr 15, 2012 #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 89 if the air passes over the top and bottom surfaces at speeds of 260 and 160 , respectively?

    3. The attempt at a solution
    um...i understand that the higher velocity of the air above the wing creates a lower pressure than below the wing and this difference in pressure generates lift, however i dont really see how bernoullis principle applies
  2. jcsd
  3. Apr 15, 2012 #2
    Hi bfusco,

    I think we could help a bit more if you told us what exactly you meant by 'Bernoulli's principle' here; there are a lot of different kind of similar things that can be labeled 'Bernoulli's principle', and I don't want to steer you wrong. Qualitatively, you already stated & explained how Bernoulli's principle applies here in your original post. In terms of the algebra, you could apply the first equation under 'incompressible flow' on the wikipedia page titled 'Bernoulli's Principle' (treating the difference in z above and below the wing as negligible), but I obviously can't promise that this is what your instructor wants you to do. I think you understand the physics here already; if there's something about the algebra that doesn't make sense, we'll need more details.

    Hope this helps,
    Bill Mills
    Last edited by a moderator: Apr 16, 2012
  4. Apr 16, 2012 #3


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    Homework Helper

    For this problem, it doesn't matter, since you're being told to use Bernoulli's equation along with the speeds you're given to calculate pressures.

    The problem statement doesn't include an alitude (which is needed to determine density), so my guess is that your supposed to assume this occurs at sea level and use the density of air at sea level.
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