  We show that any second order dynamic equation on a configuration space $X\to
R$ of nonrelativistic mechanics can be seen as a geodesic equation with respect
to some (nonlinear) connection on the tangent bundle $TX\to X$ of relativistic
velocities. We compare relativistic and nonrelativistic geodesic equations, and
study the Jacobi vector fields along nonrelativistic geodesics.

General Relativity and Quantum Cosmology