Question

1. Two trains 110 m and 100 m long are
running on parallel tracks, in the same
direction with a speed of 46 km/hr and
39 km/hr, respectively. How long will it
take them to be clear of each other?​

Answer 1

Answer:

In the question, the position of the trains at t0 is not given. So I will take t0 when the faster train’s head is at the tip of the slower trains tail. And assuming that the speeds mentioned are respective and the faster train will cross the second.

|——————————-|120m (54 kmph)

………………………………|———————-|100m (72 kmph)

So the total distance the faster train needs to travel to cross the slower train is 220m

………………………|——————————-|120m (54 kmph)

|———————-|100m (72 kmph)

And the relative speed is S1 - S2 = 72–54 = 18 kmph or in mps 18*5/18 = 5 ms/s

So time taken to travel the distance = distance/speed = 220/5 = 44 seconds