Re: [Phys-l] question about Bernoulli

[brian whatcott <betwys1@sbcglobal.net>]

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.