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Pressure of a bubble in Liquid

  • #1

Homework Statement



Air is trapped above liquid ethyl alcohol in a rigid container. If the air pressure above the liquid is 1.1 atm, determine the pressure inside a bubble 4.0 m below the surface of the liquid.

Homework Equations



P= P(nought) + (density)(gravity)(height)
density of alcohol .806 x 10^3

The Attempt at a Solution



Pnought would be the 1.1 atm
P= 1.1 + (806 kg/m^3)(9.8 m/s^2)(4 m)
= 31596

That isn't the right answer, so I'm very confused. Do I need to change atmospheres to kPas? Is that density correct? Am i even using the right equation?
 
Last edited:

Answers and Replies

  • #2
hage567
Homework Helper
1,509
2
I would definitely convert the 1.1 atm to Pa to see if that's your problem. Your units aren't consistent the way they are.
 
  • #3
It isnt [tex]P_0*\rho gh[/tex]
Its [tex]P_0 + \rho gh[/tex]
 
  • #4
hage567
Homework Helper
1,509
2
P= P(nought) x (density)(gravity)(height)
density of alcohol .806 x 10^3

The Attempt at a Solution



Pnought would be the 1.1 atm
P= 1.1 + (806 kg/m^3)(9.8 m/s^2)(4 m)
= 338.22

That isn't the right answer, so I'm very confused. Do I need to change atmospheres to kPas? Is that density correct? Am i even using the right equation?


You've got two versions of the equation written down here. The one you used in your calculation is the right one, but I can't figure out how you got the 338.22 even if it is wrong.
 

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