The differential geometry of curves is applied to the dynamics of a particle moving in tridimensional space. The geometric properties of the trajectory are expressed in terms of dynamical quantities associated with the motion. In particular, we study how curvature and torsion are connected with the force on the particle. General conditions are found that a force has to satisfy in order that the trajectory lies on a plane irrespective of the initial conditions.
differential geometry of curves; single particle dynamics
