On Galilean connections and the first jet bundle

We express the first jet bundle of curves in Euclidean space as homogeneous
spaces associated to a Galilean-type group. Certain Cartan connections on a
manifold with values in the Lie algebra of the Galilean group are characterized
as geometries associated to systems of second order ordinary differential
equations. We show these Cartan connections admit a form of normal coordinates,
and that in these normal coordinates the geodesic equations of the connection
are second order ordinary differential equations. We then classify such
connections by some of their torsions, extending a classical theorem of Chern
involving the geometry associated to a system of second order differential
equations.