posted by Please help this time?? Becca on .
A train travels between stations 1 and 2. The engineer of the train is instructed to start from rest at station 1 and accelerate uniformly between points A and B, then coast with a uniform velocity between points B and C, and finally accelerate uniformly between points C and D until the train stops at station 2. The distances AB, BC, and CD are all equal, and it takes 5.00 min to travel between the two stations. Assume that the uniform accelerations have the same magnitude, even when they are opposite in direction. How much of this 5.00 min period does the train spend b/w points A & B? B & C? C & D?
I'm not sure how I'm supposed to set up the equation. I know avg v= delta x over delta t, but I can't get it so that it works.
The average V while accelerating and decelerating is half the uniform velocity between B and C. If all three distances are equal, it will therefore take twice as long to do AB or CD as it will to travel BC. That means 2/5 of the time is spent accelerating and decerlating, and 1/5 at constant velocity (BC).
You had the right equation in mind, but just needed to follow through with the logic.