Vertical distance of water inside an downward vessel

[Tulatalu]

Homework Statement

A vessel of internal volume 9 m^3 is lowered with its mouth downward into fresh water lake until the volume of the air in the vessel becomes 5 m^3. Given that the atmosphere pressure is 760 mmHg, what is the verrtical distance of the water level inside the vessel from the surface of the lake? Temperature remains unchanged. Density of water = 1000 kg/ m^3 of mercury = 13600 kg / m^3

Homework Equations

The Attempt at a Solution

I don't know how to approach this problem. Is it right that the pressure inside the vessel is the same as the atmosphere pressure? What formula should i base on to calculate the height of water ?[/B]

 

[BvU]

Hi Tulu,

If you find a relevant equation, you find your answer. Is there a context to this problem, or was it in a chapter about optics ?

 

[Tulatalu]

Hi BvU,
It's in an examination paper which consists of many problems from random topics so I'm afraid we will have to figure out the solution.

 

[BvU]

I see. Still, we need two relevant equations. Anything you have to couple p and V ? And what about pressure under water as a function of depth ?

 

[Tulatalu]

Pressure=height x density x g and pV = constant ?

 

[Tulatalu]

Pressure=height x density x g and pV = constant ?

 

[BvU]

Bingo.

Make a little drawing (actually, two: one for when the vessel touches the surface (*) and one for when the volume inside is 5 m3).
Fill in the known variables and you're done !

(*) because, as you say "the pressure inside the vessel is the same as the atmosphere pressure" at that point