1. The problem statement, all variables and given/known data A train passes a platform with velocity v. Two clocks are placed on the edge of the platform seperated by a distance L and synchronized relative to the platform inertial system. Clock 1 reads 4:00 when it coincides with the front of the train, and clock 2 reads 4:00 when it coincides with the rear of the train. Answer questions relative to an observer on the train. [Emphasis mine] (a) What is the length of the train? (b) What is the reading of the clock 2 when clock 1 coincides with the front of the train? (c) What is the time interval between the two end events? 2. Relevant equations Lorentz Transformations 3. The attempt at a solution Before answering a, b and c, I actually need to understand this question. Here are my qualms: 1. If the part of the question in bold refers to observations from the platform frame, then I don't understand how the clocks can be synchronised. The clocks read 4:00 at different times(events). 2. If it refers to observations from the train, then it seems to me to be in contradiction with what the author says a few pages earlier. It is proved that given a pair of clocks, which are synchronised in a frame in which they are at rest, moving in the the same direction and seperated in space, the leading clock lags behind the trailing one(the exact amound being Lv/c2, L- measured distance between clocks). If that is true, then howcome clock 1(leading clock) reads 4:00 before clock 2(trailing). What am I missing? For those interested, this is problem 2.4 from Richard Mould's Basic Relativity (Springer).