Question

Two trains of the same length are running in parallel tracks in the same direction with speeds of 30 km/hr and 45 km/hr respectively. The 2nd train completely crosses the 1st train in 60 seconds. The length of each train (in meters) is
1. 125 m
2. 130 m
3. 150 m
4. 170 m
5. 90 m

Answer 1

Correct Answer - Option 1 : 125 m

Speed of 1^st train = 30 km/h

Speed of 2^nd train = 45 km/h

Time taken by 2^nd train to cross 1^st train completely = 60 seconds

Concept:

When two trains cross each other, they cover a distance equal to the sum of their lengths with relative speed.

Formula Used:

Total Length = Time × Relative speed

Calculations:

Let's take the length of each train to be x.

When two trains cross each other, they cover a distance equal to the sum of their lengths with relative speed.

The total length of both trains = 2x

Time taken by 2^nd train to cross 1^st train completely = 60 seconds

Relative speed = 45 – 30 = 15 km/h

⇒ 15 × 5/18 = 25/6 m/s

∴ Total Length = Time × Relative speed

⇒ 2x = 60 × 25/6

⇒ x = 10 × 25/2

⇒ x = 125 m

The length of each train is 125 m.