Gravity Near the Earth's Surface: Geophysical Application

When we apply the gravitaional force to the gravitational force between the Earth and an object at its surface,

m(1) becomes the mass of the Earth m(E) .

m(2) becomes tge mass of the object m.

r becomes the distance of the object from the Earth's centre = radius of the earth

The force of gravity due to the Earth is the weight of the object mg.