Absolute pressure with container

[physicsdreams]

Homework Statement

A 1.00m tall container is filled to the brim, partway with mercury and the rest of the way with water. The container is open to the amosphere. What must be the depth of the mercury so that the absolute pressure on the bottom of the container is twice the atmospheric pressure?

Homework Equations

P₂ = P₁ + (rho)gh

The Attempt at a Solution

I know that the pressure at the bottom has to be 2*10^5 Pa, but I'm just not sure how to approach the rest of the problem. How do I deal with the split densities?

 

[ehild]

Both the column of mercury of height y and water of height 1.00-y contributes to the pressure of the bottom, and the contributions add up.

ehild

 

[physicsdreams]

Both the column of mercury of height y and water of height 1.00-y contributes to the pressure of the bottom, and the contributions add up.

ehild

Do I assume that the water is underneath the mercury? or does it not matter?

 

[physicsdreams]

Does this equation work?:

P₂=p₁+(rho)gh_mercury+(rho)g(1-h)_water

 

[SteamKing]

Which fluid is denser? Mercury or water?

 

[ehild]

Do I assume that the water is underneath the mercury? or does it not matter?

It does not matter in te equation (it is correct), but mercury is much denser than water...

ehild

 

[physicsdreams]

Thanks everyone, I managed to solve the problem.