I understand the concepts behind SR and Lorentz transformations and was explaining the basics to my son by illustrating the classic laser-beam-in-a-train-car explanation. But then I started thinking... If I was in a boxcar w/ a clear wall and was throwing a ball straight up, measuring the time from toss to catch, and then computing the average speed... and an observer was standing outside and performed the same measurement s/he would see the ball take a much longer route than I would (assuming the train was moving at, say, 100 kph). That means we would have a significant disagreement about the average speed we compute for the ball. Am I correct on this? It seems bizarre that two observers would see such different path lengths at everyday (non-relativistic) speeds. ?