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Question: Does someone know why they measure the gravity of earth at sea level?

(Posted by: Coops.. on 2010-03-08 04:15:58)

Posted by: Wyman on 2010-03-08, 04:16:55

It is a reference ellipsoid

Posted by: Retsum on 2010-03-08, 04:23:47

The gravitational field at a distance R from the centre of the Earth is g(R) = GM/ R^2 If R = R[E], the radius of the Earth g(R[E]) = GM/ R[E]^2 = 9.8 N/ kg (approximately)

Posted by: schase10353 on 2010-03-08, 04:55:38

Since the Earth is spinning, it is a little squished, which makes it non-spherical. Recall that the further you get from the center of the earth, the weaker gravity gets. Sea level is the average level of where the "outer radius " of the earth should be (but mountains and valleys can through that number slightly off. Measuring from sea level will let you derive an equation that expresses the amount of gravity at that spot on the Earth. In other words, sea level can sort of be looked at as the average level when considering the mountains and valleys because if you take distance from the height of the tallest peak in an area to it's lowest valley, you typically will get 0, which corresponds to (ta da!) sea level.