Question

Two trains running in opposite directions on parallel tracks, at speed of 42 km/hr and 48 km/hr, take 10 seconds to cross each other. If the length of one train is 100 m. then the length of the other train is:
1. 100 m
2. 125 m
3. 150 m
4. 110 m

Answer 1

Correct Answer - Option 3 : 150 m

Given:

Speed of both trains = 42 km/hr and 48 km/hr

Time taken to cross each other = 10 seconds

Length of one train = 100 m

Concept used:

When two bodies are moving in the opposite direction, the relative speed is calculated by adding the speed of both the bodies

Calculation:

Relative speed = (42 + 48) km/hr = 90 km/hr = 90 × (5/18) = 25 m/s

Distance travelled by both trains in 10 seconds = (25 × 10) = 250 m

Length of other train = (250 – 100) m = 150 m

∴ The length of other train is 150 m