Chapter 37, Problem 5Q

Figure 37-18 shows two clocks in stationary frame S (they are synchronized in that frame) and one clock in moving frame S'. Clocks C₁ and $C_1^{\text{'}}$ read zero when they pass each other. When clocks $C_1^{\text{'}}$ and C₂ pass each other, (a) which clock has the smaller reading and (b) which clock measures a proper time?

Figure 37-18 Question 5.