Between two stations a train acclerates uniformly at first, then moves with constant velocity and finally s uniformly. If the ratio of the time taken be 1:8:1 and the max speed attained be 60km/h then what is the average speed over the whole journey?

Answer 1

avg velocity when accelerating or deaccelerating = 30km/hr

So assume t=10 hrs

first hour, distance=30km/hr*1hr
last hour, distnace=30km/hr*1hr
middle time, distance=60km/hr*8=480km

avg velocity=total distance/time=you do it.

Answer 2

12km/hr