Force of attraction between particles that have mass.

The force of gravity ‘felt’ between two particles is directly proportional to the product of the masses of the two particles, and inversely proportional to the square of the distance between them.

##F = (Gm_1m_2)/r^2##

Where:

• ##G## is the gravitational constant
• ##m_1## and ##m_2## are the masses of the two particles
• ##r## is the distance between the two particles