the polar diameter of the earth in km is 12,714.
what is the polar diameter of the earth in km?
12,714
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instead of the seconds pendulum method, the commission of the french academy of sciences – whose members included lagrange, laplace, monge and condorcet – decided that the new measure should be equal to one ten-millionth of the distance from the north pole to the equator (the quadrant of the earth's circumference), measured along the meridian passing through paris. apart from the obvious consideration of safe access for french surveyors, the paris meridian was also a sound choice for scientific reasons: a portion of the quadrant from dunkirk to barcelona (about 1000 km, or one-tenth of the total) could be surveyed with start- and end-points at sea level, and that portion was roughly in the middle of the quadrant, where the effects of the earth's oblateness were expected to be the largest. the spanish-french geodetic mission combined with an earlier measurement of the paris meridian arc and the lapland geodetic mission had confirmed that the earth was an oblate spheroid. moreover, observations were made with a pendulum to determine the local acceleration due to local gravity and centrifugal acceleration; and these observations coincided with the geodetic results in proving that the earth is flattened at the poles. the acceleration of a body near the surface of the earth, which is measured with the seconds pendulum, is due to the combined effects of local gravity and centrifugal acceleration. the gravity diminishes with the distance from the center of the earth while the centrifugal force augments with the distance from the axis of the earth's rotation, it follows that the resulting acceleration towards the ground is 0.5% greater at the poles than at the equator and that the polar diameter of the earth is smaller than its equatorial diameter.
seconds pendulum