Define ‘G’ ( gravitational constant) in terms of ‘F’ ( force ) . – Gravitation

From Newton's Law of Gravitation: 

\(F=\frac{Gm_1m_2}{d^2}\)

when two bodies have unit and mass separated through unit distance from their centers, then

\(F=\frac{G\times1\times1}{1^2}\)

therefore, F = G

Thus, universal gravitational constant can be defined as the gravitational force between two unit masses which are separated by a unit distance.

The gravitational constant 'G' is the proportionality constant that in the Newton's Universal Law of Gravitation. The constant in Newton's law of gravitation is defined as the constant that we get when attractive force between two bodies is multiplied by the product of the masses of the two bodies and divided by the square of the distance between the masses. The constant is measured in Nm²/kg². Gravitational constant is also known as Newton's Constant.