/sci/ - Science & Math

>>11250960
>>11250900
The decrease in air pressure at the surface of the water is exactly equal to the decrease in hydrostatic pressure wherever the gage is located. That is: Say you have state (1) where the water is at its normal height and air is at 1 atm, then your gage reads 0 psig. Then you have state (2) where some air has been evacuated. If the pressure if the air has decreased by 5 psia, then the gage will read -5 psig. (psia and psig being absolute and gage pressures, respectively)
The decrease in pressure of the air is proportional to the mass of dry air evacuated. You can try treating the air as an ideal gas but keep in mind that its temperature will drop when its specific volume suddenly increases. There is software called Thermo-Calc that you can use, or you can use ye olde steam tables for this. The height of the box is completely irrelevant to the air.

>>11250960
The decrease in air pressure at the surface of the water is exactly the same as the decrease in hydrostatic pressure wherever the gage is location. That is: Say you have state (1) where the water is at its normal height and air is at 1 atm, then your gage reads 0 psig. Then you have state (2) where some air gas been evacuated. If the pressure if the air has decreased by 5 psia, then the gage will read -5 psig. (psia and psig being gage and absolute pressures)
The decrease in pressure of the air is proportional to the mass of dry air evacuated. You can try treating the air as an ideal gas but keep in mind that its temperature will drop when its specific volume suddenly increases. The height of the box is completely irrelevant to the air.