sentripetale

Sentripetale is a term used in physics to describe the inward-directed acceleration that keeps an object moving along a circular path. It is not a separate force; rather, it is the net force component directed toward the center of the circle that produces circular motion.

In uniform circular motion, the centripetal (sentripetale) acceleration a_c points toward the center and has magnitude a_c = v^2 / r = ω^2 r, where v is the tangential speed, r is the radius, and ω is the angular velocity. If the moving object has mass m, the net inward force F_c required is F_c = m a_c = m v^2 / r = m ω^2 r. This inward force is provided by whatever physical interaction governs the motion, such as gravity, tension, friction, or a component of a contact force.

A key distinction is that centripetal (sentripetale) force is not a separate kind of force; it is the inward component of the resultant force toward the center. In a rotating reference frame, a fictitious centrifugal force appears outward, but in an inertial frame the motion is described solely by the inward centripetal acceleration produced by real forces.

Examples include a satellite held in orbit by gravity, a car turning in a curve where friction provides the inward force, and a conical pendulum where the string’s tension has an inward component balancing the motion along a horizontal circle. The concept is fundamental to understanding any motion along a circular path.