How do I solve this?
The usual partial pressure of oxygen that people get at sea level is .20 atm, that is, a fifth of the usual sea level air pressure. People used to 1 atm air pressure begin to become light headed at about .10 atm oxygen. As a rule of thumb, the air pressure decreases one inch of mercury each thousand feet of altitude above seal level. At what altitude should airplane cabins be pressurized? Up to about what altitude should you be able to use unpressurized pure oxygen? (Express your answer in feet above Mean Sea Level, or MSL.)
See your earlier posts.
All you wrote was see above.
I answered the FIRST time you posted and when you went back you didn't go back far enough. Here is the original post.
http://www.jiskha.com/display.cgi?id=1270011834
To solve this problem, we need to combine the information given about the partial pressure of oxygen at different altitudes and the rate at which the air pressure decreases with altitude. Here's how you can approach it:
1. Identify the given information:
- Usual partial pressure of oxygen at sea level: 0.20 atm
- Altitude at which people become light-headed: 0.10 atm
- Air pressure decreases by 1 inch of mercury per thousand feet
2. Convert the given air pressure values in terms of atmospheric pressure at sea level:
- Usual partial pressure of oxygen at sea level: 0.20 * 1 atm = 0.20 atm
- Altitude at which people become light-headed: 0.10 * 1 atm = 0.10 atm
3. Determine the altitude at which the partial pressure of oxygen decreases to 0.10 atm:
- Since air pressure decreases by 1 inch of mercury per thousand feet, we need to find how many thousand feet it takes for the pressure to decrease from 1 atm to 0.10 atm.
- 1 atm - 0.10 atm = 0.90 atm
- To convert 0.90 atm to inches of mercury, use the conversion factor: 1 atm = 29.92 inches of mercury
- 0.90 atm * 29.92 inches of mercury = 26.928 inches of mercury
- The pressure decreases by 1 inch of mercury per thousand feet, so we divide the change in pressure (26.928 inches of mercury) by the rate of decrease (1 inch of mercury) to find the altitude in thousand feet.
- Altitude in thousand feet = 26.928 / 1 = 26.928 thousand feet
- Therefore, the altitude at which the partial pressure of oxygen decreases to 0.10 atm is approximately 26.928 thousand feet above Mean Sea Level (MSL).
4. Determine the altitude at which airplane cabins should be pressurized:
- Since people become light-headed at 0.10 atm, it is ideal to maintain the cabin pressure above this level.
- Therefore, airplane cabins should be pressurized up to the altitude where the partial pressure of oxygen reaches 0.10 atm, which is approximately 26.928 thousand feet above MSL.
5. Determine the altitude up to which unpressurized pure oxygen can be used:
- Since the usual partial pressure of oxygen at sea level is 0.20 atm, and unpressurized pure oxygen would provide a similar partial pressure of oxygen, it is reasonable to assume that it would be effective at altitudes where the partial pressure of oxygen is 0.10 atm.
- Therefore, unpressurized pure oxygen can be used up to the altitude of approximately 26.928 thousand feet above MSL.
Remember to account for approximate values and any assumptions made during calculations.