Two trains with lengths 126 m and 119 m respectively are moving towards each other. Their speeds are 12 m/s and 23 m/s, respectively. What will be the time needed by the trains to cross each other?

Question: Two trains with lengths 126 m and 119 m respectively are moving towards each other. Their speeds are 12 m/s and 23 m/s, respectively. What will be the time needed by the trains to cross each other?

Solution:
To cross each other completely, the two trains must cover a total distance equal to the sum of their lengths.
∴ Total distance to be covered = 126 + 119 = 245 meters

Since they are moving towards each other, their relative speed is the sum of their individual speeds.
∴ Relative speed = 12 + 23 = 35 m/s

∴ Time taken to cross each other = Total distance/Relative speed
= 245/35
= 7 seconds

∴ The trains will take 7 seconds to completely cross each other.