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Pressure In Liquids

According to the kinetic theory, liquids are also composed of many small particles, but in contrast to gases where the particles are very far apart, liquid particles are often touching.

Liquid water is much more dense than air, and one liter of it contains many more particles and much more mass than an equivalent volume of air. When you dive into a lake, you can feel the pressure of the water above you even if you are just a few meters below the surface because your body is supporting a lot of weight. Doubling your depth below the surface causes the pressure on your body to also double.

Fill an empty juice can with water and put two holes down one side. Place one hole near the top of the can and one near the bottom. The water coming out of the bottom hole will shoot out much further than the water escaping from the hole near the top. This is because the water at the bottom of the can is supporting the weight of the water column above it and so it is under greater pressure.

Lou D'Amore


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Atmospheric pressure

—Earth's gravitational force pulls the surrounding air towards Earth. The force created by this action causes atmospheric pressure.

Kinetic molecular theory

—The theory that explains the behavior of matter in terms of the motion of the particles that make it up.


—The SI unit of force. One newton is roughly the force exerted by the Earth on a 0.1 kg mass. This is about equal to the force exerted upward by your hand when supporting a medium sized apple.

SI system

—An abbreviation for Le Système International d'Unités, a system of weights and measures adopted in 1960 by the General Conference on Weights and Measures.

Additional topics

Science EncyclopediaScience & Philosophy: Positive Number to Propaganda - World War IiPressure - The Kinetic Molecular Theory Of Gases And Pressure, Atmospheric Pressure And Common Measuring Units For Pressure