Re: [Phys-l] Bernoulli Effect

["Anthony Lapinski" <Anthony_Lapinski@pds.org>]

This sounds reasonable, but then I always wondered how certain planes can
fly upside-down. Are the wings on these planes shaped differently?

Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu> writes:
> OK, even Algebra-based college physics students ask this kind of  
> thing; so, let me give this a try...
>
> Let's look at 2 particles, one goes over the wing, and one goes  
> under.  If the one going under the wing goes faster (shorter distance  
> and shorter time) it gets to the end of the wing first, while the  
> other particle is still over the top of the wing.
>
> This makes the next 2 particles do the same.  After a while the  
> particles will 'back up' on top of the wing.  If that were the case,  
> the density would have to become greater over the wing, pushing down  
> more on the wing, and it would not fly!
>
> Since this clearly doesn't happen, we can appeal to the equation of  
> continuity and Bernoulli's equation to 'rectify' this problem by  
> showing that the particles over the top must go faster, which means  
> the top pressure is lower.
>
> Does that help/work?
>
> Peter Schoch
> SCCC
>
> On Dec 15, 2007, at 1:59 PM, David Abineri wrote:
>
> > In describing the Bernoulli effect to high school students I  
> > invariably
> > get stuck on one particular question and I wonder if someone can help
> > give me the "high school" words necessary to answer this question.
> >
> > When looking at the cross section of a wing, I have always said that  
> > the
> > air flow under the wing (which is a relatively flat surface) is slower
> > than the air flow over the top of the wing which is curved.  The
> > question from them is "why isn't it just as likely that he air over  
> > the
> > top of the wing does not speed up and simply takes a longer time to
> > travel the longer distance over the curved section of the wing?".
> >
> > Any assistance would be welcome.  Thanks,    David Abineri
> >
> >
> >
> > -- 
> > D. Abineri     dabineri@fuse.net
> >
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