Question

A train of length 100m takes 1/6th of a minute to cross another train 150m long coming from the opposite direction.If the speed of the first train is 60km/hr,then the speed of the second train is

Answer 1

To calculate the speed of second train:

• As both trains are moving in opposite directions to each other;

Relative speed = Sum of the speed of both trains.. That is, V₁ + V₂

• Total length of both trains: 100m + 150m = 250 metres

• Total time taken for both trains to cross each other: 1/6 of a minute:-

                1 minute = 60 seconds;  so 1/10 (60) = 6 seconds

• We know that time equals distance by speed. (Time = Distance/speed)

                So;  6 = 250 / (V₁ + V₂) →  V₁ + V₂ = 250/6

• Velocity of first train is known : 60km/hr ( to be converted into m/s)-

                (60 × 1000) / 3600 → 6000/3600 = 10/6 m/s

• As previously calculated,  V₁ + V₂ = 250/6 :

                  V₂ = 250/6 - 10/6 = 240/6 → 40m/s (answer)..

• { If required, the answer can be converted into km/h from m/s; by) -

                   (40 × 3600 ) / 1000 = 144 km/hr  }