Fluid+Pressure

Fluid Pressure  ** By: Nathalee C. ** Table of Contents

= = 1. Fluid Pressure 2. What Causes Fluid Pressure? 3. Air Pressure 4. Balanced Pressure = ﻿  =

 **Fluid Pressure **
 * Fluids exert pressure. A fluid is material that flows. This causes fluids to be able to change shapes. Some examples of fluids are liquids and gases. (Jones 76) **

What Causes Fluid Pressure? ** The tiny particles that make up a fluid constantly move in all directions. When they move they collide with any other particles or any other surface. When each particle hits a surface it exerts a force on the surface. “All of the forces exerted by the individual particles in a fluid combine to make up the pressure exerted by the fluid” (Jones 76). Since the number of particles is large, the fluid is considered as a whole. This means that the fluid pressure is the total force that is exerted by the fluid divided by the area in which the total force is exerted. **

Air Pressure Balanced Pressure ** Then how is it possible that your hand can support this without feeling it?This happens because in a stationary fluid, pressure at a certain point is exerted equally in all directions. The weight in atmospheric pressure presses on your hand from every direction. This causes the two pressures to balance each other out. **
 * We live at the bottom of 100 km of fluid that surrounds the Earth. This fluid is air. Air is a mixture of the gases that make up the Earth’s atmosphere. These gases always press down on everything in the Earth’s surface. “Air pressure exists because it has mass” (Jones 76). Each cubic meter of air has a mass of about 1kg. The force of gravity pulls down on the mass of air. This causes the air to have weight. Air or atmospheric pressure is produced by the weight of air. (Jones 76) **
 * If you hold your hand out palm up, you’re holding air. Once at sea level the atmospheric pressure is approximately 10.13 N/cm squared. The total surface of our hands is about, if not, 100 cm squared. This means that the weight supported by our hands is about 1,000 newtons or the same weight of about a large washing machine. **
 * Balanced pressure also explains why the large amount of air that is pushing on us from all sides doesn’t crush us. Our bodies contain fluids that exert outwards pressure. Some examples are your lungs and sinus cavities that contain air. Also blood vessels and cells contain liquids. This means that the fluids from inside your body balance out the air outside of our bodies. **
 * When air pressure becomes unbalanced the outside air pressure can crush us. (Jones 77) **

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 * Sources: **

Jones, Griffith. Science Explorer Motion, Forces, and Energy. Upper Saddle River, NJ: Pearson, 2009. 93-94. Print.

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