Ask A Scientist Chemistry Archive

Question:  I know that weight and mass are different, but how is mass 
measured when there is no gravitational pull on an object?
ssm

Answer 1:
Mass is determined by measuring the inertia of an object.  That is, "its
resistance to an effort made to change its state of motion" (right from
the textbook).  So whenever you "weigh" something out, you're actually
'massing' it out.  A balance compares a known mass quantity to what is
in question.  So you could use a balance on the moon because you'd
be comparing the mass of your object to the mass it takes to realign the
beam.  (Theoretically this would work, but I guess it would take some
know-how to get your object to stay on the beam!)  How about measuring
the volume your object displaces, then if you know its density, just
multiply the two numbers.  Just some thoughts...
-Joe Schultz
 
Answer 2:
rcwinther would like to add:
"Attach the mass to one end of a spring whose spring constant K is known
with the other end of the spring fixed.  Pull the mass in order to stretch
the spring parallel to itself and let go, so that the system oscillates.
Measure the period of oscillation; denote this length of time by T.
Then m = (K * T^2)/(4 * pi^2)."
-JS