A railway train is travelling through a long tunnel at a speed of 77 km/h and...

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A railway train is travelling through a long tunnel at a speed of 77 km/h and occupies 75% of the tunnel cross-section. The air within the tunnel as a whole is at rest. The barometric reading and the air temperature within an undisturbed tunnel section are 625 mmHg and 15°C respectively. The density of air mercury is 13550 kg/m³. Neglecting compressibility and frictional effects of air flowing through the clearance between the train and the tunnel walls: (a) Determine the air velocity relative to the walls of the train. The key to this is to change the frame of reference such that we are "riding" with the train and we consider the flow past the train. (Ans: 85.56 m/s) (b) Calculate the change in the barometric reading as the train is passing by the barometer. (Ans: 25.8 mmHg) A railway train is travelling through a long tunnel at a speed of 77 km/h and occupies 75% of the tunnel cross-section. The air within the tunnel as a whole is at rest. The barometric reading and the air temperature within an undisturbed tunnel section are 625 mmHg and 15°C respectively. The density of air mercury is 13550 kg/m³. Neglecting compressibility and frictional effects of air flowing through the clearance between the train and the tunnel walls: (a) Determine the air velocity relative to the walls of the train. The key to this is to change the frame of reference such that we are "riding" with the train and we consider the flow past the train. (Ans: 85.56 m/s) (b) Calculate the change in the barometric reading as the train is passing by the barometer. (Ans: 25.8 mmHg)

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a 77 kmh 77 x 1000m 36005 77 Kmth 2139mls ... View the full answer