Why does the faster the gas velocity, the less pressure?

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The atmospheric pressure around the fast speed decreases, which is the theorem.

For example, when you take a train, there will be a yellow cordon on the ground because the atmospheric pressure around the train is less than the outside air when the train is passing quickly.

pressure, the outside air pressure will squeeze you in, so there will be a cordon.

The balloon is the same, the faster the speed, the smaller the surrounding air pressure, and the atmospheric pressure pushes all the air out of the balloon, so the balloon gets smaller and smaller.

Bernoulli's equation.

The basic conclusion of fluid mechanics was indeed done in an experimental course at the university. The equation itself applies to incompressible homogeneous non-viscous fluids, but the conclusion applies to fluids.

p + gz + (1 2) * v 2 = constant, where p, , v are the pressure, density and velocity of the fluid, respectively; z is the plumb height; g is the acceleration due to gravity.

The terms of the above equation represent the pressure energy p, gravitational potential energy per unit volume of fluid, respectively.

g z and kinetic energy (1 2) * v 2, during the movement along the streamline, the sum remains the same, i.e., the total energy is conserved.

However, the total energy (i.e., the constant value in the above equation) may be different between the streamlines. For gases, gravity can be ignored, and the equation is simplified to p+(1 2)* v2 constant (p0), and the terms are called static pressure, dynamic pressure, and total pressure, respectively. Obviously, the increase in velocity in the flow decreases the pressure; As the velocity decreases, the pressure increases; When the velocity drops to zero, the pressure reaches its maximum (theoretically equal to the total pressure).

For example, if the same person runs 2 meters per second on the Earth, the speed on the Moon is 5 meters per second. It's the same thing.

The flow velocity causes a pressure difference between the front and back of the flowing liquid or gas, and the pressure difference in the front is greater than in the back due to the action of inertia, or the continuous action of pushing behind. In this way, the flow rate in the front is greater than that in the back, so that the liquid or gas behind is in short supply. The supply exceeds the demand, so that the liquid or gas on both sides come to fill the gap, and the tendency to fill the gap will reduce the pressure on both sides.

This led to the common experiment of blowing air in the middle of two sheets of paper, and the two sheets of paper would run together.

The greater the velocity of the gas molecules, the greater the pressure, not the lesser. There is a positive correlation between pressure and the velocity of gas molecules.

Pressure refers to the action of gas molecules on the force per unit area. When the velocity of the gas molecules increases, they have a higher kinetic energy, and the force exerted on the vessel wall when they collide also increases. Therefore, the greater the velocity of the gas molecules, the greater the collision force on the unit area, resulting in an increase in pressure.

Conversely, if the velocity of the gas molecules decreases, the force they exert on the walls of the container also decreases, and the pressure decreases accordingly.

In summary, there is a positive correlation between the velocity and pressure of the gas molecules. An increase in velocity will lead to an increase in the pressure state, and a decrease in velocity will lead to a decrease in pressure. This is due to the relationship between the velocity of the gas molecules and the force of the collision.

The frequency of collision of gas molecules on the container wall is related to the mass of the gas particles, the velocity of the gas particles, the pressure of the gas and the temperature.

The pressure of gas molecules of a certain mass remains unchanged, the average kinetic energy increases when the temperature increases, the average force of each molecule on the vessel wall increases, and the pressure remains unchanged, so the number of collisions of gas molecules per unit area per unit time on the container wall decreases. Conversely, the lower the temperature, the more collisions will occur.

The result of the increase in the number of collisions per unit area of the gas molecule per unit time is an increase in pressure, which has nothing to do with the volume, indicating that the number of moles of the gas remains unchanged, and the other is the isobaric heating, so the result obtained according to the above formula is an increase in volume.

In steady flow, the flow rate through any cross-section is the same, i.e., S1 V1=S2 V2, the flow rate is the same, the cross-sectional area with large flow velocity is small, according to P=F S, the larger V P is, the smaller. Therefore, in gases and liquids, the higher the flow velocity, the lower the pressure.

Daniel Bernoulli was the first to propose the relationship between fluid pressure and fluid velocity in 1726: in a water or air flow, if the velocity is small, the pressure is great, and if the velocity is large, the pressure is small. Airplanes are able to fly into the sky because the wings are subjected to upward lift.

The streamline distribution of the air around the wing when the aircraft is flying refers to the asymmetry of the shape of the wing cross-section, the streamline above the wing is dense and the flow velocity is large, and the streamline below is sparse and the flow velocity is small. From Bernoulli's equation, the pressure above the wing is small, and the pressure below is strong. This creates a lift force in the direction acting on the wing.