Introduction to Classical Mechanics · Problem 11.31
Relativity (Kinematics) — Morin
Physics — Mechanics · overtaking-a-train
Problem
Train A has length L. Train B moves past A (on a parallel track, facing the same direction) with relative speed 4c/5. The length of B is such that A says that the fronts of the trains coincide at exactly the same time as the backs coincide. What is the time difference between the fronts coinciding and the backs coinciding, as measured by B?