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發問:
Assume that at all elevations, T = 0 degree Celsius and g = 9.80 m/s^(2). At what altitude above sea level is air pressure 90% of the pressure at sea level? The answer is 850 m. Please show the steps. Thank you very much. 更新: Can you tell me what is the meaning of 'exp' ? Thank you very much!!!
最佳解答:
The variation of pressure P with altitude h is given by, P = (Po).exp(-Mgh/RT) where Po is the pressure at sea level M is the molar mass of air, taken to be 29 g/mol (= 2.9 x 10^-2 kg/mol) R is the Universal gas constant (=8.31 J/mol.K) T is the absolute temperature Hence, P/Po = 0.9 = exp(-Mgh/RT) = exp(-2.9x10^-2 x 9.8h/(8.31 x 273)) solve for h gives h = 841 m For derivation of the pressure formula, please refer to http://www.math24.net/barometric-formula.html 2012-12-02 19:38:43 補充： The first sentence should read: For variation of pressure P with altitude h is given by,
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Physics Question!!!Thx!!!發問:
Assume that at all elevations, T = 0 degree Celsius and g = 9.80 m/s^(2). At what altitude above sea level is air pressure 90% of the pressure at sea level? The answer is 850 m. Please show the steps. Thank you very much. 更新: Can you tell me what is the meaning of 'exp' ? Thank you very much!!!
最佳解答:
The variation of pressure P with altitude h is given by, P = (Po).exp(-Mgh/RT) where Po is the pressure at sea level M is the molar mass of air, taken to be 29 g/mol (= 2.9 x 10^-2 kg/mol) R is the Universal gas constant (=8.31 J/mol.K) T is the absolute temperature Hence, P/Po = 0.9 = exp(-Mgh/RT) = exp(-2.9x10^-2 x 9.8h/(8.31 x 273)) solve for h gives h = 841 m For derivation of the pressure formula, please refer to http://www.math24.net/barometric-formula.html 2012-12-02 19:38:43 補充： The first sentence should read: For variation of pressure P with altitude h is given by,
其他解答:
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