### Newton's law for Gravitational Force

Gravitational Force →

Newton's Gravitational Law statement is a combination of three individual statements. These are
1. The force between the two-particle is directly proportional to the product of their masses i.e.

$F \propto m_{1} \: m_{2} \qquad(1)$

Where $m_{1}$ & $m_{2}$ are the masses of the particles.

2. The force between the two-particle is inversely proportional to the square of the distance between them i.e.

$F \propto \frac{1}{r^{2}} \qquad(2)$

Where $r$ is the distance between the particles.

3. This force always acts between the line joining the masses.

From the above the equation $(1)$ and equation $(2)$

$F\propto \frac{m_{1} \: m_{2}}{r^{2}}$

 $F=G \frac{m_{1} \: m_{2}}{r^{2}}$

Where $G$ is Newton's gravitaional constant and its experimental value $6.67\times 10^{-11} \frac{N-m^{2}}{kg^{2}}$

Properties of Newton's law for Gravitational force →

There are the following properties of Newton's law for gravitational force

• Gravitational force is always an attractive force.

• Gravitational force is action and reaction pair and follows Newton's third law.

• A Gravitational force is a conservative force.

• Gravitational force is central force i.e. it is always acting along the line joining between two particles.

• Unit and Dimensional formula of $G$

The unit of $G$ is $\frac{N-m^{2}}{kg^{2}}$

The dimensional Formula of $G$ is $[M^{-1}L^{3}T^{-2}]$