Question

wo trains are travelling in opposite directions at uniforms speeds of 60 kmph and 50 kmph.they take 5 seconds to cross each other.if the two trains travelled in the same directions.then a passenger sitting in the faster moving train would have overtaken the other than in 18 seconds.what are the lengths of the trains?

Answer 1

Let length of faster train and slower train be x and y respectively

When they travel in opposite direction, trains cross each other in 5 sec
Relative speed = 60+50 =110 km/hr =

110×5

18=55018

110×518=55018

m/s
Distance travelled = x+y
Time taken to cross each other = 5 s

(x+y) =

550×5

18=13759

550×518=13759

---(1)

When they travel in same direction, passenger sitting in the faster moving train would have overtaken the other train in 18 sec
Relative speed = 60-50 =10 km/hr =

10×5

18=5018

10×518=5018

m/s

Since the observation given is of a passenger sitting in faster train, distance travelled is equal to length of the slower train.
i.e, distance travelled = y m

Time taken for overtaking = 18 s

y =

5018×18

5018×18

= 50 m

From(1), x + 50 =

13759

13759



x =

13759−50=9259

13759−50=9259