# Apparent force

## apparent force

(Also fictitious force, inertial force, transport force.) A force (mass times an acceleration) introduced on the side of an equation on which all supposedly real forces appear.

For Newton's dynamical law of motion for a body of mass m acted on by a force F, to be valid requires that the acceleration a be specified relative to an inertial reference frame. If the acceleration in a noninertial reference frame (e.g., a rotating reference frame) is a*, then and the previous dynamical equation may be written where the quantity - mai is the inertial or apparent force and ai is the inertial acceleration. Examples of apparent forces are the centrifugal force and the Coriolis force. Within classical (Newtonian) mechanics inertial forces are fictitious, merely masses times accelerations. But in general relativity, inertial forces are equivalent to real forces resulting from interactions between bodies because it is impossible to distinguish between inertial and gravitational accelerations; both are independent of the mass of the body.
See apparent gravity.

Symon, K. R. 1960. Mechanics. 2d ed., . p. 271.

Bergmann, P. G. 1942. Introduction to the Theory of Relativity. 155–156. 