Re: Electronic balances was A weighty subject

[Bob Sciamanda <trebor@VELOCITY.NET>]

I have lost Edminston's original post, but I am thinking eg, of an
ordinary double pan balance. This directly compares two weights and must
be accompanied by a set of labeled "standard weights" in order to yield
"absolute" results.  So both the balance and the set of labeled standards
are carried to the moon - a built-in calibration.

Whatever pairs of objects balanced on the earth will also balance on the
moon.  You may want to change the labels on the "standard weights" when
you get to the moon;  how to do this would involve comparing the weights
of the same object on the earth and on the moon - but this is an entirely
different kind of measurement - how would you do it?  You would have to
resort to eg, a spring scale along with appropriate assumptions about its
behavior on earth/moon.

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor

----- Original Message -----
From: Cliff Parker <cparker@EMPOWERING.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Wednesday, October 13, 1999 9:10 PM
Subject: Re: Electronic balances was A weighty subject


> I realize that a balance compares one weight to another but what weight
does
> an electronic balance compare to the 1.2?  I suppose you are saying that
it
> would record 1.2 if the balance was recalibrated to a know standard?
When I
> read michael Edmiston's original post I did not understand that the
balance
> was to be recalibrated once on the moon.
>
> Cliff Parker
>
> Bob Sciamanda wrote:
>
> > A balance compares one weight to another.  If on earth the specimen
object
> > balanced with the weight labeled 1.2 oz, so will it do on the moon!
> >
> > Bob
> >
> > Bob Sciamanda (W3NLV)
> > Physics, Edinboro Univ of PA (em)
> > trebor@velocity.net
> > http://www.velocity.net/~trebor
> >
> > ----- Original Message -----
> > From: Cliff Parker <cparker@EMPOWERING.COM>
> > To: <PHYS-L@lists.nau.edu>
> > Sent: Wednesday, October 13, 1999 7:39 PM
> > Subject: Electronic balances was A weighty subject
> >
> > > > I routinely switch one of them to ounces when I need to "weigh" a
> > > > letter or package that I intend to mail.  (Why convert from grams
to
> > > > ounces in my head, if the scale will do it for me.)  Now suppose
it
> > > > says that my envelope weighs 1.20 ounces.  In my lab at Bluffton
> > > > College, that is probably pretty darn close.  But if I take that
same
> > > > envelope and same balance to the moon, it will still say that my
> > > > envelope weighs 1.20 ounces... and Jim, that is wrong.
> > >
> > > Is this correct?  If so then I am in need of some insight as to how
> > electronic balances
> > > work.  Will someone please fill me in.
> > >
> > > Cliff Parker