Centripète

Centripète is a French term used in physics to describe quantities directed inward toward the center of a circular path. In English, the corresponding concept is centripetal. It denotes the inward direction of the acceleration or the net inward force that keeps an object on a circular trajectory.

In mechanics, objects in circular motion experience centripetal acceleration toward the center. Its magnitude is a_c = v^2 / r, where v is the speed and r is the radius of the circular path. The associated centripetal force F_c = m a_c = m v^2 / r is not a separate force but the net inward force resulting from the real forces acting on the object (such as gravity, tension, normal force, or friction) that point toward the center.

Centripetal quantities are described within an inertial frame of reference. In a rotating (non-inertial) frame, a fictitious centrifugal force appears directed outward, which is the frame-dependent counterpart of the inward centripetal effect.

For angular velocity ω, the centripetal acceleration can also be expressed as a_c = ω^2 r. This description remains valid whether the motion is uniform (constantω) or variable, so long as the motion is circular and the center remains fixed.

Examples include a satellite orbiting a planet, a car negotiating a curved road, or a mass on a string being swung in a circle. The term centripète is common in French-language physics texts; in English, centripetal is used more frequently.

See also: centripetal force, centrifugal force, circular motion, angular velocity, curvature.