Two trains of equal length are running on parallel lines in the same direction at 66 km and 56 km per hour. The faster train passes the slower train in 36 seconds. The length of each train is-

Question: Two trains of equal length are running on parallel lines in the same direction at 66 km and 56 km per hour. The faster train passes the slower train in 36 seconds. The length of each train is-

Solution:
To cross each other, two trains have to cover a distance equal to the sum of the lengths of the train.
Let the length of the trains be = a m each.

So the distance to be covered = 2a
Now the trains are running int he same direction.
∴ Their relative speed = (66 - 56) km/hr.
=10km/hr. = 10 × (5/18) km/hr. = (25/9) m/sec.

So, the time taken by the trains to cove 2a m distance
= 2a ÷ (25/9) sec

∴ By the given conditions,
2a ÷ (25/9) = 36
⇒ 2a × (9/25) = 36
⇒ 2a = (36 × 25)/9
⇒ 2a = 100
∴ a = 50

So, the length of each train = 50 m.