Problem on Trains
- Two trains 70 m and 80 m long respectively, run at the rates of 68 km and 40 km an hour respectively, on parallel rails in opposite directions. How long do they take to pass each other ?
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Total distance = 70 + 80 = 150 m
Relative speed = 68 + 40 = 108 kmph = 108 x (5/18) = 30 m/sCorrect Option: A
Total distance = 70 + 80 = 150 m
Relative speed = 68 + 40 = 108 kmph = 108 x (5/18) = 30 m/s
So time taken = 150 / 30 = 5 seconds.
- A person see a train passing over 1 km long bridge. The length of the train is half that of bridge. If the train clears the bridge in 2 minutes the speed of the train is ?
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Distance covered in 2/60 hours = (1 + 1/2) = 3/2 km
Correct Option: B
Distance covered in 2/60 hours = (1 + 1/2) = 3/2 km
Distance covered in 1 hour = (3/2) x (60/2) = 45 km
So, speed of the train = 45 km/hr
- A train 50 meters long passes a platform 100 m long in 10 second. The speed of the train is ?
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Distance covered by train in 10 sec = (50 + 100) = 150 m
Correct Option: C
Distance covered by train in 10 sec = (50 + 100) = 150 m
∴ Speed = 150/10 m/sec = 15 x (18/5) = 54 km/hr
- A train covers 90 m in passing a standing man. Find the length of the train.
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We know that, the distance covered by a train in passing a pole or a standing man or a signal post or any other object (of negligible length) is equal to the length of the train.
Correct Option: D
We know that, the distance covered by a train in passing a pole or a standing man or a signal post or any other object (of negligible length) is equal to the length of the train.
In this case, train covers 90 m to cross a standing man.
∴ Length of the train = 90 m
- A 220 m long train passes a signal post in 12 s. Find the speed f the train.?
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We know that,
Speed = Distance/ TimeCorrect Option: C
We know that,
Speed = Distance/ Time
Speed of the train = 220/12 x (18/5) km/h