The light clock in the spaceship in Figure 1-25 uses a light pulse moving up the y axis to reflect back from a mirror as the ship moves along the x axis. Suppose instead the light pulse moves along the x' axis between x' = 0 and a mirror at x' = L. 

(a) What is the time required for the pulse to make a round trip in the rest system of the spaceship? 

(b) What is the round-trip time in the laboratory frame? 

(c) Does the result in (b) agree with that expected from time dilation? Justify your answer.

Figure 1-25

(a) S' Mirror (b) YA Mirror X X (c) ( NIR [5] At D