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> This orbital velocity at the surface of the earth is some 40,320 km/sec.

Is that a typo? Orbital velocity on the surface should be 7.9km/s.

40,320 km/sec is full earth rotation per second, a tiny bit too fast . Should be /per day or so. Also, 40k km/s is ~13% of c (speed of light)

It seems like it must be - 40,320 km is comparable to the circumference of the earth!