Concept Library / Kinematics

Gravitational Field Strength

Gravitational field strength is gravitational force per unit mass:

g = \frac{F_{g}}{m} .

Its unit is $N {kg}^{- 1}$ , which is equivalent to $m s^{- 2}$ .

Full explanation

Gravitational field strength is gravitational force per unit mass:

g = \frac{F_{g}}{m} .

Its unit is $N {kg}^{- 1}$ , which is equivalent to $m s^{- 2}$ .

The gravitational field strength gives both the force experienced per kilogram and the acceleration of an object in free fall when other forces are negligible. It is a vector directed toward the attracting mass.

Formula / representation

Near Earth's surface, $g$ is commonly approximated as constant for kinematics problems. The sign used in a one-dimensional equation depends on the chosen coordinate axis; $g$ itself denotes a magnitude unless a vector/component sign is explicitly attached.

Common misconceptions

Treating $g$ as a universal constant at all locations.
Confusing gravitational field strength with gravitational force.
Writing $g$ as automatically negative rather than assigning a component sign from the axis.
Assuming equivalence of $N {kg}^{- 1}$ and $m s^{- 2}$ means force and acceleration are the same quantity.

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