On Sun, 8 Jul 2001, Bill Potts wrote: > ... > The only scales that measure mass are balance scales, ... Yes, Bill, but only if by "balance scales" you mean "devices which bring forces into static equilibrium" including springs. You give me a set of standard masses and a spring (or any of many other elastic devices, e.g. load cells) which acts as F = - k d, where F is the restoring force, d is the displacement (elongation or compression), and k is the elastic constant of the device in newtons per meter and I'll calibrate the device to measure mass at the location of calibration. > ... > However, given that they are calibrated on the Earth and in the general > geographic area where they are to be used (i.e., given the constancy of the > ratio of measured force to actual mass), the units displayed can reliably > indicate the mass placed on them. That is the point, Bill, *calibration* of elastic devices in units of mass at a particular location. e.g. the load cells at your grocery store. Gene.
