Newton's Law of Universal Gravitation

Physical Law
Every particle in the universe attracts every other particle with a force $F$ which is inversely proportional to the square of the distance between them:
 * $\mathbf F \propto \dfrac {m_1 m_2} {r^2}$

The direction of the force on either particle is the same as the direction of the displacement vector to the other particle.

Using vector notation:
 * $\mathbf F \propto \dfrac {m_1 m_2} {r^2} \hat {\mathbf r}$

where $\hat {\mathbf r}$ is the unit vector from one particle to the other.

Gravitational Constant
Thus the equation becomes:
 * $\mathbf F = \dfrac {G m_1 m_2 \mathbf r} {r^3}$

Also known as
Newton's Law of Universal Gravitation is also known as just Newton's Law of Gravitation.

However, the idea behind it may have originated with.

supposedly deduced this law from Kepler's Laws of Planetary Motion.