Chapter 2 Gravitational Field of the Earth

Publisher Summary This chapter considers the gravitational field of the earth. The chapter mentions the forces acting on elementary volume of the rotating Earth in an inertial frame and considers the second Newton's law in non-inertial system. It introduces the centrifugal force and gravitational field, as well as its potential. Special attention is paid to the gravitational field and potential, caused by an ellipsoid of rotation and derives formulas for the gravitational field outside and at the surface of the rotating spheroid with an arbitrary value of flattening f, provided that this surface is equipotential. As is well known, the earth is mainly a fluid; the upper crust is an exception, but it is extremely thin layer with respect to the earth's radius. For this reason it is natural to expect that rotation around its axis makes the shape of the earth practically the same as if it was a fluid, and we will follow this conventional point of view.