State the universal law of gravitation. Write the $SI$ unit of $G$.

(N/A) The universal law of gravitation states that every object in the universe attracts every other object with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
Mathematically,$F = G \frac{M \times m}{d^2}$,where $F$ is the gravitational force,$M$ and $m$ are the masses of the two objects,and $d$ is the distance between them.
The $SI$ unit of the universal gravitational constant $G$ is $N \ m^2 \ kg^{-2}$.