Fg (physics)

For other uses, see FG (disambiguation).

F_g is an abbreviation used in physics and engineering 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 squared. This is represented by the formula:

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

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:

$\mathbf{F}_{g} = \sum_{i=1}^{N} -G \frac{m m_i}{r_{i}^3}\mathbf{r}_{i}$