Re: [Phys-l] question about Bernoulli

[William Robertson <wrobert9@ix.netcom.com>]

Yes, I believe you can omit the hole. Doesn't Bernoulli say that the  
pressure on the inside of the syringe wall will be less than the  
pressure outside due to the increased velocity inside?

Bill


William C. Robertson, Ph.D.


On Nov 17, 2010, at 6:11 PM, brian whatcott wrote:

> Probably better to wait, as you say.    :-)
>  The reduction in air pressure in a duct due to its motion  requires  
> no
> side hole and external molecular collisions!
>
> B
>
> On 11/17/2010 6:57 PM, Bernard Cleyet wrote:
> > Not drag, but push.
> >
> > The thermal motion outside the cylinder near and at the hole  
> > results in diffusion into the cylinder.   The net motion of the gas  
> > inside is in the direction of the piston, so those molecules  
> > collide w/ those formerly outside resulting in a partial vacuum  
> > (relatively) at the hole, etc.
> >
> > bc  waiting for JD. and thinks it's similar to the operation of a  
> > diffusion pump.
>
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