Two trains each 200 m long are moving in opposite directions. They cross each other in 10 seconds. If the speed of one train is 90 km/h, find the speed of the other train.
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 54 km/h
Given:
Length of both trains = 200 m
Speed of first train = 90 km/h
Concept used:
Relative speed when vehicle is moving in the opposite direction or towards each other = x + y
Where, x and y are the speed of two trains.
Speed = Distance/time
Calculations:
Let the speed of second train be y.
Total distance = 200 + 200 = 400 m
Relative speed = x + y = 400/10
⇒ x + y = 40 m/s
Now, 40 m/s in km/h = 40 × 18/5 = 144 km/h
⇒ 90 + y = 144
⇒ y = 54 km/h