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A train of length 110 m is moving with a speed of 72 km/h and another train of length 120 m is moving with a speed of 36 km/h in opposite direction along parallel tracks. What is the time taken in seconds to cross each other?1. \(\dfrac{23}{3}\) sec2. 11.2 sec3. 23 sec4. 24 sec |
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Answer» Correct Answer - Option 1 : \(\dfrac{23}{3}\) sec Given- Length of 1st train = 110 m Speed of 1st train = 72km/hr Length of 1st train = 120 m Speed of 1st train = 36 km/hr Formula used = Distance = Speed × Time Relative Speed = Speed of Object 1 + Speed of Object 2 ( If they are moving opposite to each other) Concept Used- For a train to cross another train completely it should travel a distance equal to sum of length of both the trains. Calculation- Total distance to be covered = 110 + 120 = 230 m Speed of 1st train = 72 × 5/18 = 20 m/sec Speed of 1st train = 36 × 5/18 = 10 m/sec Their relative Speed = 20 + 10 = 30 m/sec Time taken to cross each other = 230/30 = 23/3 seconds |
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