Abstract. In the description of relative motion in accelerated systems and gravitational fields, inertial and tidal accelerations must be taken into account, respectively. These involve a critical speed that in the first approximation can be simply illustrated in the case of motion in one dimension. For one-dimensional motion, such first-order accelerations are multiplied by (1 − V²/V²_c), where is the critical speed. If the speed of relative motion exceeds V_c, there is a sign reversal with consequences that are contrary to Newtonian expectations.

PACS number: 04.20.Cv

Print publication: Issue 24 (21 December 2004)
Received 30 June 2004, in final form 22 October 2004
Published 22 November 2004