Hello, I have problem with this example. I don't speak English very well, so please forgive me if something isn't quite enough defined - as it should be in English Physics terminology. The train moves from the station with an acceleration a. After reaching velocity v moves farther with constant velocity, next train moves with deceleration and, at last to dwell on the following station. What is the average velocity of the train v(avr) on the rout in length s? I know that the answer should be v(avr) = v/(1+(v^2)/as). But I don't know how to get to it. Could somebody tell me step by step what should I do?