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Train crosses a platform of 200 m long in 90 seconds at a speed of 60 km/hr. The time taken by the train to cross an electric pole is ______.1. 78 sec2. 30 sec 3. 52 sec4. 62 sec |
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Answer» Correct Answer - Option 1 : 78 sec Given Train crosses a platform of 200 m long in 90 seconds Speed of train = 60 km/hr. Concept Speed = (Distance/Time) Speed in meter/second = (5/18) km/h When a train cross a pole it means the length of train is actual distance. Calculation Let the length of train be x meter Total distance covered by train = length of train + length of platform ⇒ Total distance covered by train = (x + 200) m. ⇒ Speed of train in meter per second = (5/18) × 60 ⇒ Speed of train in meter per second = (50/3) m/s ⇒ (50/3) = (x + 200)/90 ⇒ (50 × 90)/3 = x + 200 ⇒ 1500 = x + 200 ⇒ x = 1500 - 200 ⇒ x = 1300 meter Length of train = 1300 meter Now, ⇒ The time taken by the train to cross an electric pole = (1300/(50/3)) ⇒ The time taken by the train to cross an electric pole = 78 sec. ∴ The time taken by the train to cross an electric pole is 78 sec. |
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