[lug] Anyone else hate to get rid of old equipment?
georges at mhsoftware.com
Tue Jun 8 16:40:52 MDT 2010
Surface gravity actually varies based on your location.
A Kilogram standard is only a Kilogram at 45 degrees N Latitude, Sea Level.
Variation of latitude and altitude change local surface gravity.
Practically speaking, this is why pendulum clocks have a knob so you can
adjust the length of the pendulum so that the period of oscillation is
In the metrology world, if you are using Weight standards like piston
dead-weight pressure gauges, and you are going for a certain degree of
accuracy then you have to do the calculations for the adjustment. For this
area, it's about 0.1%.
Using the pendulum clock example, a variation of .1% is 86.4 seconds per
Davide Del Vento wrote:
Absolutely, you are right, the analogy works up to a point. You can
raise the ball to the same level it was yesterday, change something in
the room (temperature, pressure) or put a sticker on the ball surface
and let it fall over and over again. You cannot put the climate at the
level it was last century, change something (did that volcano erupt?)
and redo the experiment. Moreover, lot of statistics is required for
climate study, whereas not so much is required for gravity (at least
for the Newton theory).
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