A train is moving at a speed of 20 m/s and crosses a pole in 8 seconds. How long will it take to cross another train which is running in opposite direction at double speed and half the length of the first train?
Answer with explanationAnswer: Option C
Since the speed of the train is 20 m/s and it takes 8 seconds to cross the pole, so the length of the train is 20 × 8 = 160 metres
Now the other train is coming at double speed = 40 m/s and its length is half = 80 metres
So the total length to be crossed becomes = 160 + 80 = 240 meters
And the relative speed becomes 40 + 20 = 60 m/s
Therefore, the time taken = 240/60= 4 seconds