Absolute pressure at the bottom of a container

The equation should be P = ρgh + P(atmospheric), where ρ is the density of the oil (800 kg/m^3) and h is the total depth of the container (49 cm). The atmospheric pressure is added at the end, not multiplied. This will give the correct answer of 191932 Pa. In summary, the absolute pressure at the bottom of a container filled with 20.0 cm of water and a 29.0-cm-thick layer of oil with specific gravity 0.800 is 191932 Pa. The correct equation to use is P= ρgh+ P(atmospheric), where ρ is the density of the oil and h is the total
  • #1
kimlu
11
0

Homework Statement



A container is filled to a depth of 20.0 cm with water. On top of the water floats a 29.0-cm-thick layer of oil with specific gravity 0.800. What is the absolute pressure at the bottom of the container?
(Answer in Pa)

Homework Equations



P= ρgh+ P(atmospheric)

The Attempt at a Solution



(800)(9.81)(29-20)+101.3x10^3= 171932

Webassign says "Your response differs from the correct answer by more than 10%. Double check your calculations."

Did I substitute something wrong?
 
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  • #2
Hi kimlu...

You have to calculate pressure at the bottom of the container ,not between the interface of water and oil .

You also seem to have forgotton to convert 'cm' to 'm' .
 
Last edited:
  • #3
kimlu said:

Homework Statement



A container is filled to a depth of 20.0 cm with water. On top of the water floats a 29.0-cm-thick layer of oil with specific gravity 0.800. What is the absolute pressure at the bottom of the container?
(Answer in Pa)

Homework Equations



P= ρgh+ P(atmospheric)

The Attempt at a Solution



(800)(9.81)(29-20)+101.3x10^3= 171932

Webassign says "Your response differs from the correct answer by more than 10%. Double check your calculations."

Did I substitute something wrong?

Yes.

Why did you subtract the thickness of water from the thickness of oil?

ehild
 

Related to Absolute pressure at the bottom of a container

1. What is absolute pressure at the bottom of a container?

Absolute pressure at the bottom of a container is the total pressure exerted by a fluid or gas at a specific point at the bottom of the container. It includes both the atmospheric pressure and the additional pressure created by the weight of the fluid or gas above the point.

2. How is absolute pressure at the bottom of a container different from gauge pressure?

Absolute pressure at the bottom of a container takes into account the atmospheric pressure, while gauge pressure only measures the difference between the total pressure and the atmospheric pressure. Absolute pressure is always higher than gauge pressure.

3. What factors affect the absolute pressure at the bottom of a container?

The main factors that affect absolute pressure at the bottom of a container are the density of the fluid or gas, the height of the fluid or gas column, and the acceleration due to gravity. These factors determine the weight of the fluid or gas above the point and therefore the total pressure.

4. How is absolute pressure at the bottom of a container measured?

Absolute pressure at the bottom of a container can be measured using a pressure gauge or a manometer. These devices use mechanical or electronic mechanisms to measure the pressure and display it in units such as Pascals, atmospheres, or pounds per square inch (psi).

5. Why is it important to know the absolute pressure at the bottom of a container?

Knowing the absolute pressure at the bottom of a container is crucial in many industrial and scientific applications. It helps in understanding the behavior of fluids and gases in closed systems, designing and maintaining pressure vessels, and ensuring the safety and efficiency of various processes that involve pressure differentials.

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