A train, 500 m long, passes a railway platform 400 m long, in one minute with uniform speed. What is the time (in seconds) taken by the train to pass a man riding a motorbike,travelling opposite to the direction of the train, at a speed of 18 km/h?

25

We know , 

Speed = \(\frac{Distance}{Time}\)

= \(\frac{500 + 400 }{60}\) = 15 m/sec

Speed of man on bike = 18 km/h = 5 m/sec

Relative speed ( when moves in opposite direction ) = 15 + 5 = 20 m/sec

Tome to cross man = \(\frac{500}{20}\) = 25 sec