Question

Two clocks, labelled 1 and 2, are at rest in an inertial frame , S. They are synchronized and separated by a distance, d, as measured in S. A third clock, 3, at rest in S', moves from clock 1 to clock 2 at constant speed, v. An observer in S' measures the distance between clocks 1 and 2 to be 0.72 d. 10 seconds elapses on clocks 1 and 2 in the time taken for clock 3 to travel between them.

(a) Event 1 is when clocks 1 and 3 are coincident. Event 2 is when clocks 2 and 3 are coincident. (Coincident simply means 'in the same place'.) Which of clocks 1, 2 and 3 measures events 1 and 2 to be separated by a proper time?

(b)  10 seconds elapses on clocks 1 and 2 in the time taken for clock 3 to travel between them. Calculate the amount of time elapsed on clock 3 as it moves between clocks 1 and 2.

(c) Calculate the relative speed of the two inertial frames, v, as a fraction of the speed of light, c.

Answer 1

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