A rocketship of proper length d travels at constant velocity v relative to a frame S. The nose of the ship (A') passes the point A in S at t = t' = 0, and at this instant a light signal is sent out from A' to B' (the end of the ship).
(a) When, by rocketship time (t'), does the signal reach the tail (B') of the ship?
(b) At what time t1, as measured in S, does the signal reach the tail (B') of the ship?
(c) At what time t2, as measured in S, does the tail of the ship (B') pass the point A?