# Bernoulli's Principle !

** An animation demonstrating Bernoulli's principle: liquid flows through a system of pipes at a constant rate. Liquids flow faster through the narrow sections of pipe.**

In fluid dynamics, **Bernoulli's principle** states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.The principle is named after Daniel Bernoulli who published it in his book *Hydrodynamica* in 1738.

Bernoulli's principle can be applied to various types of fluid flow, resulting in various forms of **Bernoulli's equation**; there are different forms of Bernoulli's equation for different types of flow. The simple form of Bernoulli's equation is valid for incompressible flows (e.g. most liquid flows and gases moving at low Mach number). More advanced forms may be applied to compressible flows at higher Mach numbers.

Bernoulli's principle can be derived from the principle of conservation of energy. This states that, in a steady flow, the sum of all forms of energy in a fluid along a streamline is the same at all points on that streamline. This requires that the sum of kinetic energy, potential energy and internal energy remains constant. Thus an increase in the speed of the fluid – implying an increase in both its dynamic pressure and kinetic energy – occurs with a simultaneous decrease in (the sum of) its static pressure, potential energy and internal energy. If the fluid is flowing out of a reservoir, the sum of all forms of energy is the same on all streamlines because in a reservoir the energy per unit volume (the sum of pressure and gravitational potential *? g h*) is the same everywhere.

Bernoulli's principle can also be derived directly from Isaac Newton's Second Law of Motion. If a small volume of fluid is flowing horizontally from a region of high pressure to a region of low pressure, then there is more pressure behind than in front. This gives a net force on the volume, accelerating it along the streamline.

Fluid particles are subject only to pressure and their own weight. If a fluid is flowing horizontally and along a section of a streamline, where the speed increases it can only be because the fluid on that section has moved from a region of higher pressure to a region of lower pressure; and if its speed decreases, it can only be because it has moved from a region of lower pressure to a region of higher pressure. Consequently, within a fluid flowing horizontally, the highest speed occurs where the pressure is lowest, and the lowest speed occurs where the pressure is highest.

The **Bernoulli Equation** can be considered to be a statement of the conservation of energy principle appropriate for flowing fluids. The qualitative behavior that is usually labeled with the term "**Bernoulli** effect" is the lowering of fluid pressure in regions where the flow velocity is increased.

The popular explanation of lift. Students of physics and aerodynamics are taught that**airplanes fly** as a result of **Bernoulli's principle**, which says that if air speeds up the pressure is lowered. Thus a wing generates lift because the air goes faster over the top creating a region of low pressure, and thus lift.

**Bernoulli's principle**. **Bernoulli's principle** describes the relationship between the pressure and the velocity of a moving fluid (i.e., air or water ). **Bernoulli's principle**states that as the velocity of fluid flow increases, the pressure exerted by that fluid decreases.

**Bernoulli's principle** says that as a fluid's velocity increases its pressure decreases. Airplanes and birds **have** an airfoil shape to each of their wings to produce lift. ... Faster moving fluids create less pressure, so the bottom of the wing creates greater pressure producing lift.