A. A 125-m-long train begins uniform acceleration from rest. The front of the train has a speed of 30m/s when it passes a railway worker who is standing 225m from where the front of the train started. What will be the speed of the last car as it passes the worker?

B. In the design of a rapid transit system, it is necessary to balance the average speed of a train against the distance between stops. The more stops there are, the slower the train's average speed. To get an idea of this problem, calculate the time it takes a train to make a 9.0km trip in two situations. 1. The stations at which the trains must stop are 1.8km apart (a total of six stations, including the end stations). And 2. The stations are 3.0km apart (a total of four stations including the end stations). The train accelerates at 1.1m/s² until reaching a speed of 90km/h and then stays at that speed until it decelerates at -2m/s² in time to stop at the next station. The train stops for 20s at each intermediate stop.