Re: [Phys-l] definitions ... purely operational, or not

["Rauber, Joel" <Joel.Rauber@SDSTATE.EDU>]

Alphonsus stated in part:

> Quoting "Rauber, Joel" <Joel.Rauber@SDSTATE.EDU>:
>
> > Your rising hot air balloon is not in free-fall.  Free-fall means,
> > that there are no other influences acting on the object then
> > gravitational.  So to determine the weight of the hot-air balloon
> > with the "Bartlett" definition we need to evacuate the atomosphere,
> > or at least the local region where you are determining the weight
> > force on the balloon, measure its free fall acceleration in the
> > desired frame of reference and then compute m*g_free-fall.
> >
> > So I conclude that it is not problematic but is well-defined.
>
> Is it practical to evacuate the atmosphere based on this operational
> definition?

:-)

It is not an operational definition in the usual sense of the word; perhaps a "gedanken operational definition".  Less seriously, I intended a bit of irony in my phrase "evacuate the atmosphere"; probably you intended some as well with your response.

> This is not "Bartlett" definition. The ISO standard ISO 31-3 (1992)
> defines weight as follows:

In the context of the thread and with the use of quotes around the word 'Bartlett' and in view of the recent TPT article I stand by referring to it as the "Bartlett" definition within this conversational thread.  Since you mention the ISO standard, I assume that we agree that what I refer to as the "Bartlett" definition is equivalent to the ISO definition?  Though I prefer Bartlett's wording (less use of the subjunctive.)

> The weight of a body in a specified reference system is that force
> which, when applied to the body, would give it an acceleration equal
> to the local acceleration of free fall in that reference system.
>
> Bartlett's paper in TPT should have cited ISO standard ISO 31-3 (1992).

Yes, he should have cited it as well as some of Iona's work that you mention in another post.

Regards and Salutations:

Joel Rauber