Does a balance (either one, beam or electronic) make a mass comparison?
I don't know. Answer the following and I'll be able to give you an
answer consistent with what you seem to expect.
(1) When you put a mercury thermometer in a water bath are you measuring
the temperature of the water? How about if you use a thermocouple or an
RTD?
(2) When you read the current from a photomultiplier are you measuring
the light intensity?
(3) When you measure the potential of a pH electrode are you measuring
pH?
This list goes on and on. There aren't many measurements for which we
make a direct measurement or comparison. We almost always measure
something that is proportional to the thing we say we are measuring.
If you answer no to questions like (1), (2), and (3) and say, for
example, that the digital meter hooked to a photomultiplier measures a
voltage that is proportional to the current that is proportional to the
light intensity... then I will say that a balance makes a force
comparison (or do we want to say the beam balance makes a torque
comparison). If you answer yes to (1), (2) and (3) then I will say that
a balance makes a mass comparison.
I think we should be consistent here. Why do we make a special case for
mass and try to choose our words so carefully when we aren't doing the
same thing for all the other measurements we make?
Michael D. Edmiston, Ph.D.
Professor of Physics and Chemistry
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu