Question
A man is running at 6 m/sec in the same direction of a
train. The train crosses him in 5 seconds. If speed of the train is 108 km/hr, find the time to cross a bridge of 90 metres.Solution
Train speed = 108 × (5/18) = 30 m/sec
Relative speed = 30 - 6 = 24 m/sec
L / 24 = 5 ⇒ L = 120 metres
Time to cross bridge = (120 + 90)/30 = 210/30 = 7 seconds
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