Question

Calculate the density ratio at an altitude of 11000 m from the Mean Sea Level under ISA conditions. Write your answer correct upto two decimal places.​

Answer 1

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Answer 2

0.22 is the density ratio

Explanation:

• We have, $\frac{\rho}{\rho_0} = \frac{P}{P_0} \times \frac{T}{T_0}$ where rho is the density, P is the pressure, T is the temperature.

• We have under ISA conditions, 29.92 in. (1,013.25 mb) and 59°F (15°C) as standard sea-level temperature and pressure, and 1.29 kg/cu.met. as the standard density of air.

• We have under ISA conditions 226.321 mb as standard pressure and  -56.5°C as the standard temperature at 11,000 m

Therefore,

                      $\frac{\rho}{\rho_0} = \frac{P}{P_0} \times \frac{T}{T_0}\\\\\frac{\rho}{1.29} = \frac{226.321}{1013.25} \times \frac{216.5}{288}\\ \\\therefore \rho = 0.2166$

• To 2 decimal places, 0.2166 becomes 0.22 hence the required density ratio is 0.22