Question: This problem makes the point that what a clock reads and how much time elapses on it are not necessarily the same thing.
Ann observes two clocks moving past her at 0.8c, as shown in Fig. 11.16. She sees they are 16 light minutes apart and that as the right-hand clock comes by her, it reads 0 and her wristwatch reads 0.

a. What is the proper length between the clocks? ("Proper length" means the length measured in the rest frame.)

b. What does her wristwatch read when the left-hand clock passes her?

c. If the two moving clocks have been synchronized in their rest frame, what does Ann find the left-hand clock to read when her wristwatch reads 0?

d. How much time will have gone by on the right-hand clock when the left-hand one passes Ann? Explain.

Fig. - Two clocks moving past a stationary observer