Correct Answer - Option 2 : 84 km / h
Given:
Train length is 130m
The speed of the train is 120 km/h
Moving in the same direction of a train 140 m, and crosses in 27 seconds
Concept used:
When two objects move in the same direction speed is subtracted
When two objects move in the opposite direction speed is added.
Speed = Distance/Time
To convert speed km/h into m/s we multiply by 5/18 and vice versa
Calculation:
Total length is
⇒ 130 + 140 = 270 m
Let the speed of the other train be s km/h
Let Relative speed be r = 120 - s
⇒ r = 270/27 = 10 m/s
Convert speed into km/h multiply by 18/5
⇒ 10 × (18/5) = 36 km/h
Speed of the other train is
⇒ 36 = 120 - s
⇒ s = 120 - 36 = 84 km/h
∴ The speed of the other train is 84 km/h