It is a physical quantity of kind acceleration, with dimension of length per time squared and units of metre per second squared (m·s−2).
The g-force is an instance of specific force measured in units of the standard gravity (g) instead of m/s², i.e., in multiples of g (e.g., "3 g").
This is because accelerometers measure the proper acceleration produced by the g-force exerted by the ground (gravity acting alone never produces g-force or specific force).
In open channel hydraulics, specific force (
) has a different meaning: where Q is the discharge, g is the acceleration due to gravity, A is the cross-sectional area of flow, and z is the depth of the centroid of flow area A.