Absolute pressure with container

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Homework Help Overview

The problem involves a container filled with mercury and water, where the objective is to determine the depth of mercury needed for the absolute pressure at the bottom to be twice the atmospheric pressure. The subject area pertains to fluid mechanics and pressure calculations.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss how both the mercury and water contribute to the pressure at the bottom of the container. Questions arise regarding the arrangement of the fluids and the implications of their densities on the pressure calculations.

Discussion Status

Participants have explored various interpretations of the problem, including the contributions of different fluid heights to the overall pressure. Some guidance has been provided regarding the equation used to calculate the pressure, and there is acknowledgment of the density differences between mercury and water.

Contextual Notes

There is a mention of the container being open to the atmosphere and the need to consider the split densities of the fluids involved. The original poster expresses uncertainty about how to approach the problem, particularly regarding the arrangement of the fluids.

physicsdreams
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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?
 
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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
 
ehild said:
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?
 
Does this equation work?:

P2=p1+(rho)ghmercury+(rho)g(1-h)water
 
Which fluid is denser? Mercury or water?
 
physicsdreams said:
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
 
Thanks everyone, I managed to solve the problem.
 

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