a force F directed toward a center O whose magnitude is proportional to the distance r from the center O to the point where the force is applied; numerically F = cr, where c is a constant.
A body under the influence of a quasi-elastic force has a potential energy P equal to 1/2 cr2. The name “quasi-elastic force” is derived from the analogous property of forces produced by small deformations of elastic bodies (elastic forces). For a material point under the influence of a quasi-elastic force the center O is a position of stable equilibrium. A point removed from this position will exhibit linear harmonic oscillations or describe an ellipse (in particular, a circle) about the point O.