jousivoiman

Jousivoima, or spring force, is the restoring force exerted by a deformable spring when it is displaced from its rest length. For an ideal linear spring the force is described by Hooke's law: F = -k x, where k is the spring constant (measured in newtons per meter) and x is the displacement from equilibrium. The negative sign indicates the force acts to oppose the displacement. The corresponding potential energy stored in the spring is U = (1/2) k x^2.

In three-dimensional systems the force is directed along the spring toward the equilibrium configuration, and the linear relation is a good approximation for small deformations. Real springs can exhibit nonlinear behavior, damping, friction, and temperature dependence, especially outside the elastic range.

Spring force is central to many physical and engineering models. In a mass–spring system, the equation of motion m d^2x/dt^2 = -k x describes simple harmonic motion, with natural frequency ω = sqrt(k/m). Springs are used for energy storage, force regulation, vibration isolation, and measurement devices. They appear in scales, vehicle suspensions, clocks, toys, and many mechanical systems where a controllable restoring force is required.

Limitations include the elastic limit, beyond which permanent deformation alters the force–displacement relationship. Real springs may also exhibit hysteresis and material fatigue. Despite these caveats, Hooke’s law provides a foundational and widely applicable description of jousivoima in many practical contexts.