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Q & A: pressure and volume under water

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Most recent answer: 01/21/2012
Q:
What would the air pressure inside an upside down cup 20 meters under seawater be to keep the water out of the cup, at least sewen eigths of the water
- Obie (age 66)
Bloemfontein Free State RSA
A:
No. The pressure goes up about 1 atm for every 10 m depth. So at 20 m depth it's about 3 atm. Since at fixed temperature the volume of a gas is about inversely proportional to pressure, the air will only fill 1/3 of the cup.

Mike W.

(published on 01/21/2012)

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