Question
A man is jogging at 4 m/sec in the same direction of a
train. The train crosses him in 6 seconds. If the train's speed is 72 km/hr, find the time it takes to cross a bridge of 48 metres.Solution
Train speed = 72 × (5/18) = 20 m/sec
Relative speed = 20 - 4 = 16 m/sec
L / 16 = 6 ⇒ L = 96 metres
Time to cross bridge = (96 + 48)/20 = 144/20 = 7.2 seconds
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