Question

An engine of 10 m length travels at 60 kmph. how long does it take to cross another train 170 m long, running at 54 kmph in the same direction

Answer 1

Given :
Length of first engine=10m
Speed of first engine=60km/h
Speed of second enigne=54km/hr
length 0f second train=170m

Relative speed=60-54=6x18/5m/s[∵Travelling in same direction]
Distance=10+170=180m

Time=distance/speed

=180x5/6x18

=900/108=8.33 sec

∴It takes 8.3 sec to cross another train running at a speed of 54km/hr in same direction.

Answer 2

Solution -

Formula- Trains with speed v1 and v2 and if both the trains are moving in the same direction then,

[Length of the train 1 - Length of the train 2](m) = [Speed of the train 1 - Speed of the train 2](m/s) X Time taken to cross(s)
...........as (distance = speed * time)

[10 + 170] (m) = [60Kmph - 54Kmph] (m/s) X Time taken

180m = 6 X 5/18 X Time taken ------------(1Km/h = 5/18 m/s)

Time taken = (180 X 18) / (6 X 5) = 108 sec

Answer - The train take 108 sec to cross another train.