Oblate spheroid with very small eccentricity

Oblate spheroid with very small eccentricity 

Suppose that we deal with a slightly oblate spheroid, ei 1. Then, making use of an expansion 

It is instructive to express e in terms of the ratio of the centrifugal force and the gravitational field at points at the equator 

Here is the magnitude of the attraction field. Correspondingly, the latter give 

From an expression for g x, derived in the previous section, we have 

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Oblate spheroid with very small eccentricity... 

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