Re: magnetic lines like these?

[LUDWIK KOWALSKI <KOWALSKIL@alpha.montclair.edu>]

Date: Wed, 13 May 1998 17:17:33 -0600 (CST)
From: Zell@act.org
Subject: Re[2]: magnetic lines like these?

> > Suppose a mixture of two gases, such as He and Ar in thermal 
> > equilibrium, is inside a long cylindrical tube. A thin alluminum 
> > window, at one end of the tube, breakes [removed very rapidly] 
> > and the mixture is ejected into the surrounding vacuum. Each atom 
> > gains a non-random velocity component along the axis. Is the 
> > average non-random velocity component for the He atoms the same 
> > as for the Ar atoms?

>  I think the thermal velocities of the atoms before the window breaks 
>  will determine their velocity components along the axis of the tube 
>  after the window breaks. ....

The argument was quite convincing for a short tube (in comparison with
the mean free paths of molecules). You assume that "thermal equilibrium 
is established only by collisions between the atoms and the walls of 
the tube".  

Is the situation different at high pressures, when gas particles collide
very frequent? Do small drops ejected from the valve of a pressure cooker 
travel faster than those whose masses are considerably larger? Why should
we assume that - and + ions ejected from the Sun (mostly e and p) have
very differnt velocities?
                                                  Ludwik Kowalski