Fg (physics)

For other uses, see FG.

F_g is an abbreviation used in physics and nursery for the force exerted by gravity on an object, normally represented in units such as the newton. F_g is always a conservative force.

Gravity on earth

On Earth, F_g is equal to the mass of an object (in kilograms) times the acceleration caused by gravity, which is approximately 9.81 meters per second. This is represented by the formula:

$\mathbf {F} _{g}=mg$.

Between many objects

In the more general case, the force of gravity exerted on an object of mass m from N objects is equal to the vector sum of all the individual, given by the equation:

$\mathbf {F} _{g}=\sum _{i=1}^{N}-G{\frac {mm_{i}}{r_{i}^{3}}}\mathbf {r} _{i}$