

The interaction of two or more objects or bodies is usually mentioned in terms of coupling. Coupling is a kind of force which connects or binds the objects or bodies together. This makes the gravitational force as a weak force.
In the case of forces like Nuclear, electromagnetic and gravitation forces, the coupling constants are different. The coupling constant for gravitation is dependent on G which is universal gravitational constant, numerically equal to 6.67 * 10-11 Nm2 / Kg2.
