**The gravitational field strength** at a point is the gravitational force exerted per unit mass placed at that point.

Hence it is defined as , where

- F
_{g }= Gravitational force - m = mass of the object placed at that point.

As the gravitational force is given by , the gravitational force experienced by an object of mass m, due to a planet of mass M is given by

we can get field strength around the planet experienced by an object of mass m as

**Note **: We know that , . Thus we can see that the acceleration due to gravity and the gravitational field strength are the same units.

Thus we can see that gravitational field strength

- is inversely proportional to the square of the radial distance from the center of the object which gives rise to the gravitational field:
- is directly proportional to the mass of the object which gives rise to the gravitational field:

Thus , where* g *denotes gravitational field strength

Extract from *Physics Stage 6 Syllabus © 2017 *NSW Education Standards Authority (NESA)