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Re: Weight and Mass



Assumptions can mislead.
The variation of g amounts in the usual run of things to 9.81 +/-
a mere 0.02 N/kg

But putting this aside allows one to forget the role of diurnal
rotation in varying g, and so forget about the possibility of
artificial rotation, as we saw.

Brian W

At 01:36 10/1/01 -0700, Bernard wrote:
brian!

I thought my assumption was only for the purpose of analyzing the equal
arm balance.

bc

brian whatcott wrote:

At 22:54 9/28/01 -0700, Bernard wrote:
I thought we assumed g was uniform?

bc

[I cleaned up the visible snarl ups in the note below]

I'd say it's much better to assume that g varies from place
in a somewhat noisy way, but with two prime features that
are easily extracted from the noise by high-scholars:
latitude and elevation.

If you can be happy with a fair estimator for the sea level value
of g with latitude, you could go with

g = g sub 45,0 *(1 - 2.59E-3 cos(2*lat)) N/kg
for g sub 45,0 (the sea level value for lat 45 deg) = 9.80665 N/kg
which is popular in some academic circles.

It turns out that at sea level, if you want to stay with
a customary value of g = 9.81 N/kg (i.e. 9.805 to 9.8149 N/kg)
you would preferably be in the locality of Lat N54 deg 36 min
to Lat N35 deg 24 min according to this estimator.

brian whatcott <inet@intellisys.net> Altus OK
Eureka!