This is an even numbered exercise so I am not able to get confirmation from the book on the correct answer. 1. The problem statement, all variables and given/known data An observer in a rocket moves toward a mirror at speed v = .8c relative to the reference frame S. The mirror is stationary with respect to S. A light pulse emitted by the rocket travels toward the mirror and is reflected back to the rocket. The front of the rocket is a distance d from the mirror (as measured by observer in S) at the moment the light pulse leaves the rocket. What is the total travel time of the pulse as measured by observers in (a) the S frame and (b) the front of the rocket) 2. Relevant equations L' = Lp*gamma 3. The attempt at a solution For frame S: I started by finding the time it takes the light to travel the distance d. I found this to be d/c. I then found the distance the rocket travels in that time to be .8d. To find the total distance the light will travel I subtracted .8d from 2d and was left with 1.2d. The time it takes, then, for the light to travel this distance is 1.2d/c. Chegg said it was d/.9c For frame S: I did the same thing only used length contraction to find the distances.