# Investigate the factors that affect the gravitational field strength

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

• Fg = 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)