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e.pramudita
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Homework Statement
On a certain day the barometric pressure at sea level is 30.1in.Hg, and the temperature is 70°F. The pressure gage in an airplane in flight indicates a pressure of 10.6psia, and the temperature gage shows the air temperature to be 46°F. Estimate as accurately as possible the altitude of the airplane above sea level.
Homework Equations
Here is the solution
https://dl.dropbox.com/u/63664351/MATS2005/Capture2.PNG
The Attempt at a Solution
https://dl.dropbox.com/u/63664351/MATS2005/Capture.PNG
Problems:
1. I derived [tex] \frac{dP}{dy} = -\frac{PM}{RT} g [/tex] But on the given solution there is no M. How come?
2. Why is T linear?
3. Where it gets a=530 and b=-24/h
4. Where it gets h=9192ft?
Given P=10.6psia, P_0=30.1in.Hg and we know 29.92in.Hg=14.7psia=1atm
then P_0=30.1*14.7/29.92=14.78843583psia
[tex] \ln \frac{10.6}{14.78843583}=-0.3329915114 [/tex]
[tex] \ln \frac{506}{530}=-0.04634033726 [/tex]
[tex] \frac{g}{24*R}=0.04914629473 [/tex]
[tex] h = 146.2120585 \text{m}= 480 \text{ft} [/tex]
If you have different approach (except ISA), please do share.
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