As a rough rule, anything traveling faster than about 0.1c
Chapter 26, Problem 6SL(choose chapter or problem)
Problem 6SL
As a rough rule, anything traveling faster than about 0.1c is called relativistic—that is, special relativity is a significant effect. Determine the speed of an electron in a hydrogen atom (radius 0.53 X 10-10 m) and state whether or not it is relativistic. (Treat the electron as though it were in a circular orbit around the proton. See hint for Problem 46.)
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