🚀 go-pugleaf

   Strictly speaking, most of the instruments we use for measuring "mass"
are actually measuring weight.  When you step on a bathroom scale, you
stretch a spring because of your weight.  When you determine the mass
of something on a balance, you're comparing the torque produced by the
weight of the object with the torque produced by another weight that
has been calibrated in some fashion.  So in that sense, we are always
"weighing" things, rather than "massing" them.  Our balances happen
to be calibrated in units of mass, but they are actually measuring
weight.
   There used to be an old experiment we did that actually measured
mass by determining the period of vibration of an object as it rode
on a platform attached to some springs.  This device would work even
in the far reaches of outer space, where the net gravitational force
on objects is negligible.  Try using a double pan balance in space!
To study body mass changes during orbital flight, astronauts actually
use a spring-mounted chair to measure their masses.

Steve Luzader
sluzader@fre.fsu.umd.edu