Question

how does the magnitude of the gravitational force on the two bodies depend on the distance of separation between them

Answer 1

Gravity is More Than a Name
The Apple, the Moon, and the Inverse
Square Law
Newton's Law of Universal Gravitation
Cavendish and the Value of G
The Value of g
Isaac
Newton compared the acceleration of the
moon to the acceleration of objects on earth.
Believing that gravitational forces were
responsible for each, Newton was able to
draw an important conclusion about the
dependence of gravity upon distance. This
comparison led him to conclude that the force
of gravitational attraction between the
Earth and other objects is inversely
proportional to the distance separating the
earth's center from the object's center. But
distance is not the only variable affecting
the magnitude of a gravitational force.
Consider Newton's famous equation
F = m • a
Newton knew that the force that caused the
apple's acceleration (gravity) must be
dependent upon the mass of the apple. And
since the force acting to cause the apple's
downward acceleration also causes the
earth's upward acceleration (Newton's third
law), that force must also depend upon the
mass of the earth. So for Newton, the force
of gravity acting between the earth and any
other object is directly proportional to the
mass of the earth, directly proportional to
the mass of the object, and inversely
proportional to the square of the distance
that separates the centers of the earth and
the object.

Answer 2

Magnitude of non-contact forces between 2 bodies is inversely proportional to the square of distances between them.