# Apparent force

From AMS Glossary

## 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 to be valid requires that the acceleration and the previous dynamical equation may be written where the quantity -

*m*acted on by a force**F**,**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*m***a**_{i}is the inertial or apparent force and**a**_{i}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.