# Bernoulli's principle

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Related to Bernoulli's principle: Pascal's principle, Bernoulli's equation

## Bernoulli's principle,

physical principle formulated by Daniel Bernoulli that states that as the speed of a moving fluid (liquid or gas) increases, the pressure within the fluid decreases. The phenomenon described by Bernoulli's principle has many practical applications; it is employed in the carburetor and the atomizer, in which air is the moving fluid, and in the aspirator, in which water is the moving fluid. In the first two devices air moving through a tube passes through a constriction, which causes an increase in speed and a corresponding reduction in pressure. As a result, liquid is forced up into the air stream (through a narrow tube that leads from the body of the liquid to the constriction) by the greater atmospheric pressure on the surface of the liquid. In the aspirator air is drawn into a stream of water as the water flows through a constriction. Bernoulli's principle can be explained in terms of the law of conservation of energy (see conservation lawsconservation laws,
in physics, basic laws that together determine which processes can or cannot occur in nature; each law maintains that the total value of the quantity governed by that law, e.g., mass or energy, remains unchanged during physical processes.
, in physics). As a fluid moves from a wider pipe into a narrower pipe or a constriction, a corresponding volume must move a greater distance forward in the narrower pipe and thus have a greater speed. At the same time, the work done by corresponding volumes in the wider and narrower pipes will be expressed by the product of the pressure and the volume. Since the speed is greater in the narrower pipe, the kinetic energy of that volume is greater. Then, by the law of conservation of energy, this increase in kinetic energy must be balanced by a decrease in the pressure-volume product, or, since the volumes are equal, by a decrease in pressure.

## Bernoulli's principle

An increase in the velocity of a fluid that is accompanied by a decrease of pressure. Swiss scientist, Daniel Bernoulli (1700-1782), demonstrated that, in most cases, the pressure in a liquid or gas decreases as the liquid or gas moves faster. This explains in part why a wing lifts an airplane.

The Lift of a Wing The curved top of a wing creates a longer distance from front to back than the straight bottom. This causes the air on top to travel farther, and thus faster, to reach the back than the air underneath, creating a difference in pressure between the two surfaces.
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References in periodicals archive ?
Bernoulli's principle states that "when an incompressible, smoothly flowing fluid gains speed, internal pressure in the fluid decreases, and vice versa" (Hewitt, 2004).
* Bernoulli's principle is commonly cited as the reason for this: Fluid pressure is inversely related to fluid velocity--as velocity increases, pressure decreases, creating lift.
Cardiovascular mechanics: Pressure, Bernoulli's principle, anatomy of the heart, and valves.
But he said his greatest contribution was the application of Bernoulli's principle, which proposes that the higher the speed of a flowing fluid, the lower the pressure and vice versa.
But he said his greatest contribution to the sport was in the application of Bernoulli's principle, which proposes that the higher the speed of a flowing fluid, the lower the pressure and vice versa.
Hands on workshops for middle school students included experimentation with gases, acid/base reactions, puzzling puzzles, electrochemistry, polymers and Bernoulli's Principle. Held on Tuesday and Wednesday, each activity was set up for 30 students to participate at each experiment station.
Although pressure forms the basis for understanding topics such as the internal structure of the earth, weather cycles, rock formation, Bernoulli's principle, and plate tectonics, the presence of this concept in the school curriculum is at a minimal level.
Boy, he would have been really nervous during my science magic show, if he had seen me put a piece of paper I had set on fire in a bottle to illustrate Bernoulli's Principle. Of course, I had a fire extinguisher near.
Each class period now has a "Web moment," in which we take a short visit to a pertinent Web site; a "media moment," in which we preview a CDROM or a similar resource; an "instant science" segment, in which we use the document projector to display real science activities; and a "junk science" segment in which we disprove such common myths as "an airplane flies using Bernoulli's principle." At the university we have a lot of evening classes that meet once a week and are two hours and 45 minutes long.

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