The gravitation force is exerted by the planet Earth ,

where is the mass of Earth.

             is its radius.

            is the gravitational constant.

             distance from the center of the earth.

Definition of continuity :

A function is continuous at , if then it should satisfy three conditions :

(1) is defined.

(2) exists.

(3) .

Condition (1): is defined.

If then the function is .

Substitute in the above function.

.

Condition (2): exists.

Left hand limit :

Right hand limit :

Left hand limit and right hand limit are equal, limit exist.

.

Condition (3): .

and .

.

The three conditions of continuity are satisfied, hence the function is continuous.

Therefore, the function is continuous at .

The function is continuous function of .