Two trains 130 m and 140 m long are running on parallel tracks in the same direction with a speed of 68 km/hr and 50 km/hr. How long will it take to clear off each other from the moment they meet?
Solution:
Relative speed of trains = (68 – 50) km/hr
= 18 km/hr
= 18 × 5/18 m/sec
= 5 m/sec
Time taken by the train to clear off each other = sum of length of trains/relative speed of trains
= (130 + 140)/5 sec
= 270/5 sec
= 54 sec
2. The two trains are running on parallel tracks in the same direction at 70 km/hr and 50 km/hr respectively. The faster train passes a man 27 second faster than the slower train. Find the length of the faster train.
Relative speed of the trains = (70 – 50) km/hr
= 20 km/hr
= 20 × 5/18 m/sec
= 50/9 m/sec
Length of the faster train = relative speed × time taken by train to pass
= 50/9 × 27 m
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