Re: Measurement of mass

[brian whatcott <inet@INTELLISYS.NET>]

Methods which invoke the inertial aspect of mass rather than its attractive
effect will evidently finesse the value of g.
 So one thinks of the acceleration of an [object of] unknown mass by [an
act providing] a known force in frictonless circumstances: perhaps a wire
suspended torsion balance, whose torsional spring constant is very much
more linear than that of a coil spring, and the determination of whose
period can use rather small excursions of the rotor. Still, you need force,
displacement and time.

To eliminate the spring constant altogether, you could possibly rig a
conservation of angular momentum apparatus to vary the arms carrying
rotating masses between known radii, and measure the angular speeds at each
extension.
Here you seem to need a value for a comparison or standard mass or masses
of the various rotating pieces, a measure of their displacement, and the time.

Brian Whatcott     Altus OK


At 13:14 10/12/99 -0600, Ken wrote:
> I have a film clip from SkyLab showing a man being masses by measuring the
> period of oscillation of a chair and him in the chair. If it is SHM then m
> is proportional to period.
>
> There is an old PSSC lab based on the same principle of inertia. It does
> require calibrating the "inertial balance" against known masses. I have
> students do this as a lesson in calibration. If they can successfully
> measure the mass of a bag of candy this way, they get to keep it. Yum!
>
> Ken Fox

> On Tue, 12 Oct 1999, romanza wrote:
>
> > ... A spring balance would measure
> > the correct weight (hence mass) if the force constant k is constant. The
> > question is then: is there a method to measure mass/weight which is
> > independent of the two assumptions described (i.e. indept of g field and
k)?
> > rom

brian whatcott <inet@intellisys.net>
Altus OK