Define the universal gravitational constant $(G)$.

(N/A) According to Newton's law of gravitation,the force between two masses is given by $F = \frac{G m_{1} m_{2}}{r^{2}}$.
If we take $m_{1} = 1 \ kg$,$m_{2} = 1 \ kg$,and $r = 1 \ m$,then $F = G$.
Therefore,the universal gravitational constant is defined as the gravitational force of attraction between two bodies of unit mass separated by a unit distance.