Inertial Force

inertial force [i′nər·shəl ′fȯrs]

(mechanics)

The fictitious force acting on a body as a result of using a noninertial frame of reference; examples are the centrifugal and Coriolis forces that appear in rotating coordinate systems. Also known as effective force.

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Inertial Force 

a vector quantity equal in magnitude to the product of the mass m of a mass point and the acceleration w of the mass point. The inertial force is opposite in direction to the acceleration. In the case of curvilinear motion, the inertial force can be resolved into a tangential component J_τ opposite in direction to the tangential acceleration w_τ and a normal, or centrifugal, component J_n directed away from the center of curvature along the principal normal to the trajectory of the mass point. Numerically, J_τ = mw_τ, and J_n = mv²ρ, where v is the velocity of the point and ρ is the radius of curvature of the trajectory. When motion with respect to an inertial frame of reference is studied, the inertial force is introduced in order to have the formal possibility of expressing equations of dynamics in the form of the simpler equations of statics.

The concept of inertial force is also used in the study of relative motion. In this case, when the “vehicle” force J_veh and the Coriolis forces J_Cor are added to the forces of interaction (with other bodies) acting on the mass point, the equations of motion of the point in a moving, or noninertial, frame of reference can be written in the same form as in an inertial frame (seeRELATIVE MOTION and CORIOLIS FORCE).

S. M. TARG