The special theory of relativity is currently included in the curricula of high school in many countries. For this reason, we often organize in-depth lessons on this topic and, in this paper, we summarize a lecture that we have given in some extra activities addressed to last year high school students stimulating pupils “to play” with Lorentz transformations. We found a simple relation that allows us to deduce the rest length of a relativistic train without knowing the relative velocity and without using the lorentz factor and spacetime distortions.
Keywords:
Special relativity; Lorentz transformations; Lorentz factor