One can also make an inertial balance. One design would be a pan
supported by two hacksaw blades standing on edge and thus parallel to
each other. One end of the pair of blades is clamped to an "immovable"
object and the other end of the pair is clamped to the pan, with one
blade on each end of the pan and overhanging a table edge (for example).
Known masses are placed in the pan and the period of oscillation is
measured for each. A calibration curve allows determination of other
masses in that range. Keeping the blades rigidly clamped at each end
forces each to assume an "ess" shape in one direction and then the
other, so the pan does not rotate as it sways from side to side. It's a
lot of fun to watch and is, perhaps, more cute than elegant.
Nonetheless, this is not unlike the construction of some oscillators
used for timing and frequency calibrations.
Jim
On Tue, 27 Feb 2001, Karl G. Ruling wrote:
> At 11:59 2/27/01 -0700, you wrote:
> >I guess to be more precise, we could say that the grain elevators infer
> >the mass by measuring the weight. It's hard (impossible?) to measure mass
> >directly.
>
>
> You spin the unknown mass around a point at a set speed, and the
> centripetal force needed to make the unknown mass follow the curved path is
> a measure of the mass.
>
> A balance beam also measures mass by comparing it with a known mass.
--
James R. Frysinger University/College of Charleston
10 Captiva Row Dept. of Physics and Astronomy
Charleston, SC 29407 66 George Street
843.225.0805 Charleston, SC 29424
http://www.cofc.edu/~frysingj [EMAIL PROTECTED]
Cert. Adv. Metrication Specialist 843.953.7644
