1. The problem statement, all variables and given/known data Two trains of proper length L move toward each other in opposite directions on parallel tracks. They both move at speed v with respect to the ground. Both trains have clocks at the front and back, and these clocks are synchronized as usual in the frame of the train they are in. A tree is located on the ground at the place where the fronts of the trains both read zero when they pass. Find the reading on the clocks at the backs of the train when they (the backs) pass each other at the tree. Do this in three different ways: a) Standing next to the tree on the ground, and you observe what one of the rear clocks is doing. b) Imagine that you are on one of the trains, observing what your own rear clock is doing during the time the tree travels relevant distance. c)Imagine that you are one of the trains, observing what the other train's rear clock is doing during the time the tree travels the relevant distance. 2. Relevant equations I'm not even sure what equations are even relevant for this problem. 3. The attempt at a solution I am so lost and don't even know where to begin with this problem. Special relativity just isn't my thing. Can someone please at least help in pointing me in the right direction?