A common sense about pressure, what is the definition of pressure?

For the same kind of crystal, the melting point is related to the pressure, and the melting point of the substance at a pressure of 1 atmosphere is generally taken as the normal melting point. At a certain pressure, both the melting point and the freezing point of the crystalline substance are the same. The melting point of a substance that expands in volume during melting increases when the pressure increases.

The boiling point is directly proportional to the air pressure. The higher the air pressure, the higher the boiling point; The lower the air pressure, the lower the boiling point.

Reason: When the liquid volatilizes it produces vapor pressure, when the vapor pressure (saturated vapor pressure) is equal to the external pressure, the liquid will boil, and the temperature at this time is the boiling point of the liquid.

When the external pressure increases, the temperature must be raised to make the vapor pressure increase to equal to the external pressure and reach boiling. When the external pressure is reduced, the vapor pressure can be equal to the external pressure when the temperature is relatively low, and the boiling can be achieved.

What we usually call the atmosphere is the entire layer of air that surrounds the earth In addition to containing nitrogen, oxygen and carbon dioxide, it also contains water vapor and dust We call the air with little moisture (i.e., low humidity) "dry air" and the air with more water vapour (i.e., high humidity) "moist air" Don't think that "dry" things are necessarily lighter than "wet" things In fact, the molecular weight of dry air is, and the molecular weight of water vapor is, so dry air molecules are heavier than water vapor molecules In the same situation, The density of dry air is also higher than that of water vapor, which is only about 62 of the density of dry air

For dry air and moist air under the same conditions, because the density of gas molecules and the average mass of molecules in dry air are larger than those of moist air, and the average momentum of dry air molecules is also greater than that of moist air, the pressure of dry air with low humidity is greater than that of humid humid air The air on cloudy days is humid and the air on sunny days is dry, so the pressure is low on cloudy days and high on sunny days.

In winter, the air pressure is relatively high in the area of the summer rain type, because there are few fish in the area of the summer rain type, and the fish is the water evaporation in the ocean that moves with the air flow to a certain area and the cold and hot confrontation and rainfall, because the air flow is from the high-pressure area to the low-pressure area, so the summer rain type area has low summer pressure and high winter pressure, while the winter rain type area has high summer pressure and low winter pressure, and the all-rain type area has a lower air pressure throughout the year.

1.That's right. There is no why. Nature.

2 It seems to be a matter of geography. I didn't listen carefully in my first year of high school.

3 winter high.

The definition of pressure is the ratio of the pressure experienced by the object to the area of the force and is called pressure.

Pressure is used to compare the effect of pressure, and the greater the pressure, the more obvious the effect of pressure.

The formula for calculating the pressure is: p=f s, the unit of pressure is pascal, and the symbol is pa. Pressure is a physical quantity that represents the effect of pressure (deformation effect).

In the International System of Units, the unit of pressure is Pascal, abbreviated as Pa (Pa), i.e. Newton square meter (n m).

Common units of pressure are bar, kilopascal (kpa), megapascals (mpa), psi, etc.

"p" refers to the pressure (note: it is a lowercase "p", not an uppercase "p", which refers to the power to do work).

The unit of pressure is "Pascal", which is abbreviated as "Pa", and the symbol is "Pa". f stands for force, the unit is "Newton", abbreviated as "Ox", and the symbol is "N".

s represents the stressed area, the unit is "square meters", and the symbol is "m".

Pressure Unit Conversion:

1 MPa (megapascals) = 1000 kPa (kilopascals) = 1,000,000 pa (pa).

1 gpa=1000 mpa=1000 000 kpa=1000 000 000 pa。

1 atm (standard atmospheric pressure) = 101325 nm, which is the pressure generated by 101325 pa (pascal) = 760 mmHg 1 MPa = 145 psi.

1 torr = 1 760 atm torr (0 pressure of 1mmHg column at standard gravity).

1 torr pa= mbar (millibar).

1 pa=1 n m =1 (kg·m s) m =1 kg (m·s) = mbar = mbar = 1/100,000 (kilogram-force square centimeter). 1 mpa=10 bar。

The definition of pressure is the ratio of the magnitude of the pressure experienced by the object to the area of the force.

The pressure symbol is p(pressure). Pressure is used to indicate the effect of pressure, and the greater the pressure, the more obvious the effect of pressure. The formula for calculating pressure is: p=f s, the unit of pressure is pascal (abbreviated as pa), and the symbol is pa.

The methods of increasing the pressure are: increasing the pressure while the force area is the same or decreasing the force area when the pressure is not the same. The square ridge blocking method for reducing pressure is as follows: reducing the pressure under the condition that the force area remains the same or increasing the force area under the condition that the pressure is not the same.

The liquid has pressure on both the side walls and the bottom of the container, and the pressure increases with the depth of the liquid.

Application of pressure:

1. Life application:

Hydraulic jacks, suck drinks with straws, suction cups stick to smooth walls without falling off, use needles to absorb water, cupping, piston pumps (according to atmospheric pressure, piston pumps can be calculated to pump water up to 10 meters), locks, water level devices, backwater elbows of sewers, etc.

2. The method of reducing the pressure of cherry blossom chaos:

When the pressure f is constant, the force area s is increased.

When the force area s is constant, the pressure f is reduced.

At the same time, the pressure f is reduced and the force area s is increased.

3. Methods of increasing pressure:

When the pressure f is constant, the force area s is reduced.

When the force area s is constant, the pressure f is increased.

At the same time, the pressure f is increased and the force area s is reduced.