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Re: Measuring acceleration of Earth



I get 30.3 and 29.4 km/s with the earth's rotation at .463 km/s and the mean
speed in orbit at 29.9 km/s.

Then v^2/R for just the orbital motion ranges from .0058 to .0061 m/s^2. So
taking g(due to mass alone) at 10m/s^2 this would account for a difference
of .0003 out of 10 or my .003%. Where am I wrong here?

Rick

----- Original Message -----
From: "John Mallinckrodt" <ajm@CSUPOMONA.EDU>
To: <PHYS-L@LISTS.NAU.EDU>
Sent: Wednesday, November 03, 2004 10:47 AM
Subject: Re: Measuring acceleration of Earth


>If you weigh something very accurately, at the equator, and at both Noon
>and
Midnight, I get that there should be about a .003% difference due to the
relative speed difference in the v^2/R term for the earth's motion around
the sun. Perhaps such a measurement could be used?

The difference in speeds is a LOT bigger than that. The orbital
speed of a point at the equator at midnight approaches 31 km/s and at
noon 29 km/s. This creates a real diurnal variation in what would be
observed as the the magnitude of the gravitational field strength.
However, it's easy to show that the magnitude of the variation is no
more than 8 angstroms/s^2, about 1 part in 10^10, so measuring it
would certainly be at least VERY difficult.

John Mallinckrodt
Cal Poly Pomona