On Fri, 14 Jun 2002, James R. Frysinger wrote: > > ... they had to first calculate the orbital speed at that > altitude (7698.85 m/s). Then they had to calculate the dilation of time > by the theory of special relativity ...
Jim, "Special Relativity" is restricted to motion at *constant relative velocity*. The international space station is in motion at *constantly changing velocity* (in constantly accelerating motion) with respect to an observer at a fixed location on the earth. *General Relativity* is required for the calculation of subtle clock discrepancies. Likewise, precise GPS determinations of positions on the earth require adjustments of parameters dictated by General Relativity. How do you present the distinction between Relativity (at constant v), and Relativity (at variable v, even v (magnitude) much less than c) to your students without the equations of general relativity? Fortunately, metrication requires no application of Relativity (restricted, or general) that is not also required by a choice of non-SI units of length and time. For example, GPS corrections apply to all non-SI units of length and time as they do to the meter and the second. Gene.
