Model of the Earth with a Constant-Density Core and a Constant-Gravity Mantle
Carol Evelyn Millar, R. Mitalas · Journal of Geoscience Education · 1998
A model of the earth, consisting of a constant-density core and a mantle in which the magnitude of gravity is constant, is developed and compared with the earth. The assumption of constant magnitude for gravity determines the density distribution in the mantle and all the physical properties of the mantle. The total mass of the earth then gives the density of the core in terms of the fractional radius of the core. The resulting pressure distribution as well as the moments of inertia of the core and mantle of the model are compared with those of the earth. The pressure and density distributions give a constant bulk modulus in the mantle. Assumption of the Poisson's ratio gives the speeds of seismic waves in the mantle, which decrease as √r in the mantle. Suggestions to use this model as a pedagogical tool in geophysical education are made.