Jon Senior <jon_AT_restlesslemon_DOTco_DOT_uk> wrote in message news:<
[email protected]>...
> half_pint [email protected] opined the following...
> > Yes it is dependent on other factors too but weight is indeed one of them.
>
> Or mass, as is the preferred terminology of most scientists. In the
> context of a discussion of "falling due to gravity" the qualification of
> "weight" is unnecessary and makes you appear to be ignorant of the
> correct terms.
Unfortunately, many of the scientific persuasion are too stupid, or
too miseducated, to understand the simple fact that "weight" is an
ambiguous word, one with several different meanings.
Weight is never a force when anybody talks about "net weight", for
example.
Weight is never a force when anybody talks about "molecular weight";
or "atomic weight" or "formula weight" either. And those are
applications in science.
Weight is never a force when anybody talks about "troy weight".
Weight is never a force when anybody talks about "carat weight".
Weight is a force when people talk about "draw weight" of a bow--but
that force has nothing to do with gravity.
It's your option not to call this quantity weight. But that's your
only option. Unfortunately, you are like many scientists, so stupid
that you think you can continue to call it "weight" but to misapply a
definition which is inappropriate and incorrect in the context--thus
your claim of redundancy here.
In fact, if you are talking about something like the weight of
bananas, if you want to make it clear that you are talking about
something different than the normal quantity that is measured for this
purpose, one effective way to do that is to specify that you are
talking about the "force due to gravity". Furthermore, that's exactly
what the ASTM recommends in American Society for Testing and
Materials, Standard for Metric Practice, E 380-79, ASTM 1979.
3.4.1.2 Considerable confusion exists in the use of the
term weight as a quantity to mean either force or mass.
In commercial and everyday use, the term weight nearly
always means mass; thus, when one speaks of a person's
weight, the quantity referred to is mass. . . .
The use of force of gravity (mass times acceleration of
gravity) instead of weight with this meaning is
recommended. Because of the dual use of the term weight
as a quantity, this term should be avoided in technical
practice except under circumstances in which its meaning
is completely clear. When the term is used, it is
important to know whether mass or force is intended and
to use SI units properly as described in 3.4.1.1, by
using kilograms for mass or newtons for force.
Here are the keepers of the standards for the U.K.
NPL FAQ
http://www.npl.co.uk/force/faqs/forcemassdiffs.html
Weight
In the trading of goods, weight is taken to mean the
same as mass, and is measured in kilograms. Scientifically
however, it is normal to state that the weight of a body
is the gravitational force acting on it and hence it
should be measured in newtons, and this force depends
on the local acceleration due to gravity. To add to the
confusion, a weight (or weightpiece) is a calibrated mass
normally made from a dense metal, and weighing is
generally defined as a process for determining the
mass of an object.
So, unfortunately, weight has three meanings and care
should always be taken to appreciate which one is meant
in a particular context.
The keepers for the standards of the U.S.
http://physics.nist.gov/Pubs/SP811/sec08.html
In any case, in order to avoid confusion, whenever the
word "weight" is used, it should be made clear which
meaning is intended.
The National Standard of Canada, CAN/CSA-Z234.1-89 Canadian Metric
Practice Guide, January 1989:
In scientific and technical work, the term "weight"
should be replaced by the term "mass" or "force,"
depending on the application.
So stop calling this quantity weight if you so choose. Just don't
insist that because somebody did call it weight that it must be the
force due to gravity, so it would be redundant to specify that.
When people talk about the "weight" of a bycycle or its components, it
is almost always mass and not the force due to gravity.
Gene Nygaard