Question

The total time taken by two trains to cross each other is 20 seconds. The speed of both the trains is 10 m/s. What is the combined length of both the trains?
1. 100 m
2. 200 m
3. 300 m
4. 400 m

Answer 1

Correct Answer - Option 4 : 400 m

Given:

Total time taken by two trains to cross each other = 20 seconds

Speed of both the trains = 10 m/s

Formula used:

Relative speed = Sum of lengths of both the trains/Time taken by two trains to cross each other

Calculations:

Let the sum of lengths of both the trains or the combined length of both the trains be x

∵ The speed of both the trains is equal, they can cross each other only if moving in the opposite direction

Relative speed = 10 + 10 = 20 m/s

⇒ 20 = x/20

⇒ x = 20 × 20

⇒ x = 400 m

∴ The combined length of both the trains is 400 m