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

[carmelo@pacific.net.sg]

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?

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

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).


Best regards,
Alphonsus