Pressure, is the ratio of a force acting on a surface, to the area of the surface; it is thus distinct from the total force acting on a surface. Units of pressure are force units divided by area units. Examples of these are pounds per square inch, dynes per square centimeter, or newtons (N) per square meter (Pressure n.pag). Pressure has many influences and effects on objects. When the pressure rises, it affects the melting point and the boiling point of a substance. This causes the raising of the melting and boiling points of most substances (Pressure The… n.pag). Pressure can be seen and demonstrated in many ways; including air pressure, Bernoulli’s principle, Pascal’s Principle, and Archimedes Principle.
Air pressure is the force exerted on you by the weight of tiny particles of air, called air molecules (Sample n.pag). The air’s pressure is caused by the weight of air that presses down on the earth, the ocean, and the air (Understanding…n.pag). Even though they can’t be seen, they still have weight and take up space. Air molecules are very spaced out and can be compressed to fit in a smaller volume. When the air is tightly compressed, the air is under high pressure. We are continuously feeling air pressure but we are used to the air pressure around us at sea level so we don’t consciously feel it. But when one travels higher the number of air molecules decreases and thus the air pressure also decreases. When this happens, certain symptoms can be noticed, such as a shortness of breath and the popping of your ears. This pressure is measured by an instrument called a barometer (Sample n.pag). Air pressure is reported in inches of mercury in the U.S, but elsewhere they measure it in millibars, also called hectopascals (hPa). Air pressure, among other things, is used to forecast the weather. If there is a high-pressure system coming through, then cold temperatures and blue skies will result. If there is a low-pressure system, then warm, stormy weather is expected.
Bernoulli’s principle is a perfect example of how the use of pressure can be beneficial. This principle has to do with flight and is what keeps planes in the air. It has to do with the shape of the wing on an aircraft. The bottom part of the wing is flat and the top of it is curved. This means that the air flowing over the top part of the wing has to travel faster than the air going under the wing, creating less pressure on the top of the wing and more pressure on the bottom. This effect creates lift, which in turn allows the plane to fly (Bernoulli’s Principle n.pag). It also has many more practical uses. It’s used in carburetors and atomizers, in which air is the moving fluid. Also, in the aspirator, in which water is the moving fluid (Bernoulli’s Principle n.pag).
Another way pressure is used is by Pascal’s Principle. The definition states “pressure applied to a confined fluid at any point is transmitted undiminished throughout the fluid in all directions and acts upon every part of the confining vessel at right angles to its interior surfaces and equally upon equal areas” (Pascal’s Law n.pag). In other words, it’s capable of re-exerting that force many times stronger to perform a task. This is the principle behind hydraulic devices (Pascal’s Law n.pag). For example, “a force of 10 N exerted on a piston whose area is 1 sq m and which is inserted into an enclosed chamber filled with water or another fluid transmits a pressure of 10 N per sq m throughout the fluid. If a second piston, at another part of the chamber, has an area of 10 sq m, then this pressure results in a force of 10 N being exerted on each square meter of its area, or 100 N total force” (Pressure n.pag). An everyday example of something that uses a hydraulic lift is the lift used to raise a car off the ground at the mechanics shop so that it can be repaired (Pressure and Buoyancy n.pag).
Finally, buoyancy is another example that uses pressure. For underwater diving, pressure is a very serious force to be dealt with. The pressure on a diver underwater is a result of two things; the weight of the water, and the weight of the atmosphere above. The buoyant force is the force that acts upon all submerged bodies. The Archimedes Principle explains how it works. “A body immersed in a liquid, either wholly or partially, is buoyed up by a force equal to the weight of the liquid displaced by the body” (Mitev, Hristo n.pag). This is also how taking a deep breath will cause a person to rise in the water because they are increasing the amount of water they displace. (Mitev, Hristo n.pag). Most people weight a little less than the amount of water they displace. Because of this, divers need to wear diving weights in order to keep themselves under the water (Mitev, Hristo n.pag).
In conclusion, pressure is everywhere and we are just now learning how to use it to our benefit. Pressure can be seen and demonstrated in many ways; including air pressure, Bernoulli’s principle, Pascal’s Principle, and Archimedes Principle.
Pressure has many influences and effects on people, places, and things. It is a very powerful force, and with it, we can do almost anything.