# Absolute pressure with container

• physicsdreams
In summary, the problem is to determine the depth of mercury in a 1.00m tall container filled with both mercury and water in order to achieve a pressure on the bottom of the container that is twice the atmospheric pressure. The equation used is P2 = P1 + (rho)gh, where both the column of mercury and water contribute to the pressure, and mercury is assumed to be denser than water.

## 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?

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.