Question
Two trains of equal lengths take 20 seconds and 30
seconds respectively to cross a telegraph post. If the length of each train be 240 metres, in what time will they cross each other travelling in opposite direction?Solution
Speed of the first train = [240/20] m/sec = 12 m/sec Speed of the second train = [240/30] m/sec = 8 m/sec Speed = (12 + 8) m/sec = 20 m/sec Required time = (240 + 240)/20 sec = 24 sec
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