<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
Skip Navigation
Our Terms of Use (click here to view) have changed. By continuing to use this site, you are agreeing to our new Terms of Use.

Pressure in Fluids

Pressure is force per unit area and increases with depth in an incompressible fluid.

Atoms Practice
Estimated7 minsto complete
Practice Pressure in Fluids
This indicates how strong in your memory this concept is
Estimated7 minsto complete
Practice Now
Turn In
Pascal's Principle

Pascal?s Principle

Credit: Frank Kovalchek
Source: http://www.flickr.com/photos/72213316@N00/6624446347/
License: CC BY-NC 3.0

Hydraulic jacks, automobile brakes and even the lift generated on airplane wings can be explained using Pascal's principle. Pascal's principle is based on the idea that fluids at rest are incompressible, allowing very large forces to be transmitted with the application of a smaller force.

News You Can Use

  • Pascal's law was discovered during an experiment that was allegedly performed in the 1600?s. A 10 m long pole was vertically inserted into a barrel that was filed with water. As the water was poured into the vertical tube, Pascal discovered that the pressure from the water caused the barrel to burst.
  • Credit: Unknown
    Source: http://simple.wikipedia.org/wiki/File:Principe_de_Pascal.jpg
    License: CC BY-NC 3.0

    As water is poured into the top of the vertical tube, the barrel begins to burst [Figure2]


  • The modern equivalent of this can be seen in any hydraulic automobile jacks present in some household garages. Two pistons are connected together by a fluid; one piston is much smaller than the other. A small force is applied to the small piston that produces a change in pressure which is transmitted to the fluid. This pressure is given as , where  is the applied force and  is the area of the small piston. Since the pressure at the small end must equal the pressure at the large end, it is easily seen that the force on the larger piston is:

  • Discover more about hydraulic lifts: 


Show What You've Learned

Using the information provided above, answer the following questions.

  1. If you were to place a car on piston A in the video instead of piston B, would you have to apply a larger or smaller force to piston B to raise the car?
  2. Why does Pascal's law not work if you replace the fluid in a hydraulic lift with CO2 gas?
  3. In the experiment that was performed by Pascal, why did the barrel burst?

Notes/Highlights Having trouble? Report an issue.

Color Highlighted Text Notes
Please to create your own Highlights / Notes
Show More

Image Attributions

  1. [1]^ Credit: Frank Kovalchek; Source: http://www.flickr.com/photos/72213316@N00/6624446347/; License: CC BY-NC 3.0
  2. [2]^ Credit: Unknown; Source: http://simple.wikipedia.org/wiki/File:Principe_de_Pascal.jpg; License: CC BY-NC 3.0

Explore More

Sign in to explore more, including practice questions and solutions for Pressure in Fluids.
Please wait...
Please wait...