With regard to atmospheric pressure 15, with respect to atmospheric pressure

Because these are two test tubes with a very small difference in thickness, when the two test tubes are turned upside down, there is no air entering the large test tube (when the experiment is very accurate), but at this time, there is water above the small test tube, and the water will produce pressure on the bottom of the small test tube, and this pressure is small as p water gh (no need to explain it) but there is no air above the small test tube, so the upper part will not be affected by atmospheric pressure, but the lower part will communicate with the atmosphere, so the lower part will be affected by atmospheric pressure, and the pressure generated will be perpendicular to the bottom side upward, so the upward atmospheric pressure is p0

That is, the pressure is upward, the value is p0-pgh, and the direction cannot be downward, otherwise the small test tube will not rise.

No, the atmospheric pressure at the bottom of the small test tube is PO, the pressure of the water column is PGH, and the total pressure is P0- GH

After inversion, the bottom of the small test tube is subjected to the upward atmospheric pressure po, and at the same time, the downward pressure generated by the water column with a height of h between the bottom of the small test tube and the bottom of the large test tube is pgh, and the two pressures are in opposite directions, and the atmospheric pressure is much greater than the pressure generated by the water column, so it can support the small test tube and not fall down, and at the same time, it should be the water flowing off, so h is also getting smaller, that is, for the bottom of the small test tube, the upward atmospheric pressure remains unchanged, and the downward water column pressure is decreasing, so, The total pressure on the outer top of the small test tube is P0-Gh, and the direction is upward, and it will automatically rise into the large test tube.

Atmospheric pressure refers to the pressure generated by the air at a certain location on the earthThe air on the surface of the earth is affected by gravity, which produces atmospheric pressure The density of the air layer above the earth is not equal, the air near the surface layer is denser, and the air in the upper layers is thinner and less dense Since the atmospheric pressure is generated by air gravity, where the height is large, the height of the air column above it is small, and the density is also small, so the higher the distance from the ground, the smaller the atmospheric pressure Normally, below 2 kilometers, for every 12 meters of altitude increase, The atmospheric pressure is reduced by 1 mm of mercury

Both gases and liquids are fluid, and their pressures are similar, the atmospheric pressure is in all directions, and the atmospheric pressure in all directions is equal at the same location. But since the density of the atmosphere is not uniform, the liquid pressure formula cannot be applied to the calculation of atmospheric pressure

The pressure of the gas that is sealed in a container is generated by the continuous collision of a large number of gas molecules in irregular motion against the container wall, and its magnitude is not determined by the gravity of the enclosed gas

The definition of atmospheric pressure is the pressure exerted by the atmosphere on the object immersed in it.

Atmospheric pressure (abbreviated as atmospheric pressure or barometric pressure) refers to the pressure exerted by the atmosphere on an object immersed in it.

In 1654, Glick conducted the famous Magdeburg hemispheric experiment in Magdeburg, Germany, which strongly proved the existence of atmospheric pressure, which gave people a deep understanding of atmospheric pressure.

However, as early as 1643, the Italian scientist Torricelli filled a 1-meter-long thin glass tube filled with mercury (mercury) and placed it upside down in a tank containing mercury, and found that the mercury in the glass tube dropped to a height of about 760 mm and then stopped falling. The space above this 760 mm scale has no air entering and is a vacuum.

Torricelli deduced that the pressure of the atmosphere was equal to the pressure generated by the mercury column, which is known as Torricelli's experiment. The standard atmospheric pressure is: Pascal), which is equal to the pressure produced by 760 mm Hg.

Causes of atmospheric pressure:

The earth is surrounded by a thick layer of air, which is mainly composed of nitrogen, oxygen, carbon dioxide, water vapor and helium, neon, argon and other gases. It is densely distributed around the earth, with a total thickness of 1,000 kilometers, and all objects immersed in the atmosphere are subjected to the pressure of the atmosphere acting on it, just as objects immersed in water are subjected to the pressure of water. The reason why atmospheric pressure is generated can be explained from different angles:

1. The air is affected by gravity, and the air is fluid, so there is pressure in all directions. To put it in more detail, due to the attraction of the earth to the air, the air is pressed on the ground, and it has to rely on the ground or other objects on the ground to support it, and these objects that support the atmosphere and the ground are subject to the action of atmospheric pressure. The atmospheric pressure per unit area is the atmospheric pressure.

2. It can be explained from the point of view of molecular motion, because gas is composed of a large number of molecules that move irregularly, and these molecules are bound to constantly collide with objects immersed in the air, and each time the gas molecules collide with each other, they must give an impact force to the surface of the object, and the result of the continuous collision of a large number of air molecules is reflected in the pressure of the atmosphere on the surface of the object, thus forming atmospheric pressure.

If there are more molecules per unit volume, the more air molecules collide with the surface of the object in the same amount of time, and the resulting pressure will be greater.

Atmospheric pressure (atmospheric pressure) generally refers to air pressure, and atmospheric pressure is the atmospheric pressure acting on a unit area, that is, the gravitational force that is numerically equal to the vertical air column that extends upward to the upper boundary of the atmosphere per unit area.

The famous Magdeburg hemispheric experiment proves its existence. The international unit of air pressure is Pascal, abbreviated as Pa, and the symbol is Pa. In meteorology, people generally use kilopascals (kpa) or hectopa (hpa) as the unit.

Other commonly used units are: bar (1 bar = 100,000 Pa) and centimeters of mercury (or centimeters of mercury). Air pressure varies not only with altitude but also with temperature. Changes in air pressure are closely related to weather changes.

According to the theory of molecular dynamics, the pressure of a gas is caused by a large number of molecules frequently colliding with the walls of the container. The collision time of a single molecule on the container wall is extremely short, and the effect is not continuous, but a large number of molecules frequently collide with the vessel wall, and the force on the vessel wall is continuous and uniform, and the ratio of this pressure to the area of the vessel wall is the pressure strength is small.

There are two types of measuring instruments commonly used in meteorology: liquid (such as mercury) barometer and solid (such as metal empty box) barometer. The barometric pressure recording is measured by a barometer or barometer installed in a barometric pressure chamber with little temperature variation and well-lit air pressure chamber, with timed barometric pressure recording and continuous barometric pressure recording.

The timed pressure record of manual visual measurement is measured by a moving trough or fixed trough mercury barometer, and the basic station observes 4 times a day and the base station observes 24 times a day. The timed air pressure record of continuous barometric pressure recording and automatic telemetry observation is recorded by using a metal elastic diaphragm box as a sensor, and the barometric pressure record can be obtained at any time.

These instruments are used to measure the air pressure of the station, and the sea level pressure can be calculated according to the sea height of the station, the air pressure of the station, the temperature of the air column and other parameters.

The air pressure is measured in heppascals, taking one decimal place; Some are also measured in millimeters of mercury column height, taking two decimal places. The conversion relationship between millimeter to heclapa is:

1 hPa = mm (height of the mercury column) 3 4 mm (height of the mercury column).

1 mm = hPa 4 3hPa.

In 1953 and before, the barometric pressure observation in China was recorded in millimeters of mercury column height, and in 1954 and later, it was recorded in the old cavity of 100 pascals.

The pressure exerted by the atmosphere on the object immersed in it is called the atmospheric pressure, referred to as atmospheric pressure or atmospheric pressure p p = kg m3 Newton kg m = Newton m2 = Pascal =1amt =76mmHg =76 Torr 1mmHg = 101300pa 76 = 1332....

For an explanation of atmospheric pressure, see " Atmospheric pressure ".

Word Breakdown Explanation of the atmosphere The gas that surrounds the earth also refers to the gas that surrounds other planets The rough breath that he exhales is so frightened that the atmosphere does not dare to be generous This child looks quite atmospheric Grand Magnificent Majestic Majestic Explain in detail. The layer of gas that surrounds the earth is a mixture of air, water vapor, and fine dust. Ye Yusen, "Bo Interpretation of Pressure: The force on the unit area is explained in detail before and trembling to explain the pressure on the unit area.