Newton’s Law of Gravitation:

[latex]F = G\frac{m_1 m_2}{R^2}[/latex]

Where, G = Universal gravitational constant.

Definition of G:

We have,

[latex]F = G\frac{m_1 m_2}{R^2}[/latex]

[latex]G = \frac{F \times R^2}{m_1 \times m_2}[/latex]

If [latex]m_1 = m_2[/latex] = 1 unit & R = 1 unit, then,

[latex]G = \frac{F \times 1^2}{1 \times 1}[/latex]

Or, G = F (numerically).

Therefore, universal gravitational constant is numerically equal to gravitational force between 2-unit mass of bodies at the unit distance.

Characteristics of Gravitational force:

i) It is always attractive force.

ii) It is independent on medium.