Question

Between two stations a train starting from rest first accelerates uniformly, then moves with constant velocity and finally retards uniformly to come to rest. If the ratio of the time taken be 1:8:1 and the maximum speed attained be 60Km/h, then what is the average speed over the whole journey?

Answer 1

Maximum speed = 60 Km/h

Minimum speed  = 60/8 = 7.5 km/h

Therefore, average velocity = (7.5 + 60 + 7.5) / 2

                          =  37.5 km/h