Atmospheric pressure in the third year of physics, and atmospheric pressure in the second year of ph

Barometer is an instrument made according to Torricelli's experimental principle and used to measure atmospheric pressure. The types of barometers include mercury barometers and aneroid barometers. Its uses are:

It can be changed in the weather, and the weather is sunny when the air pressure is high; When the air pressure drops, there will be wind and rain weather. Measurable height. For every 12 meters of elevation, the mercury column is lowered by about 1 millimeter, so the height of the mountain and the altitude of the aircraft as it flies through the air can be measured.

Pumping Pumping machine aka name. Water pump.. It is a hydraulic machine that uses atmospheric pressure to lift water from a low place to a high place.

It consists of a water pump, power machinery and a transmission device. There are many types to suit different needs. Commonly used are:

Piston pumping. And. Centrifugal water pump.

The structure of the piston pumping machine is simple, easy to operate, but the water output is small, and in the actual case of energy loss, the height of the water can only reach about eight meters, and the efficiency is also low. Centrifugal water pump is a kind of pumping machinery that uses the centrifugal movement of water, its water output is large, the water lifting height is high, and it is widely used in farmland irrigation, drainage and water supply and drainage of industrial and mining enterprises and towns.

Pumping machine One of the air extractors is a type of machine used to pump out the gas in a closed container. Generally, there are two types: hand-cranked and electric, and the main structure is similar to that of a pump. It works similarly to a water pump, except that the substance being pumped out is air.

Pump is a common tool made by using the relationship between gas pressure and volume. There is a piston in the pump, and there is a concave rubber disc on it, when the piston is pulled up, the volume of air under the piston increases, the pressure decreases, and the air above the piston is squeezed from the rubber disc to the bottom; When the piston is pressed down, the volume of air under the piston decreases and the pressure increases, so that the rubber disc is pressed against the cylinder wall to prevent air from leaking above the piston; Continue to press down on the piston, and when the air pressure is strong enough to open the rubber sleeve on the tire valve (the valve is a one-way valve), the compressed air enters the tire.

Pressure cooker The pressure cooker is made by increasing the air pressure in the pot and increasing the boiling point of water. When using a pressure cooker to cook rice, inside the lid of the pressure cooker is an airtight container. When heating, the temperature of the water in the pot continues to rise, and the evaporation of the water is also accelerating, because the pot is sealed, there is more and more water vapor above the water surface, and the air pressure in the pot is getting bigger and bigger, until the air pressure valve is jacked up to run the gas, and the air pressure in the pot does not increase.

At this time, the air pressure in the pot is generally close to one atmosphere. Under such air pressure, the boiling point of water is close to 120, and the process of food from raw to cooked is a heating process, the higher the temperature, the faster it will be cooked, so the pressure cooker will naturally cook the rice easily.

There is also drinking water through a straw.

Plastic suction cups syringes.

Pumping machine vacuum cleaner airplane flight (air pressure difference).

As shown in the picture, fill a small bottle with some colored water, then take a thin glass tube with two ends open, draw a scale on it, make the glass tube through the rubber plug into the water, and blow a small amount of gas from the upper end of the tube to make a simple barometer. Xiao Ming brought the barometer from the foot of the mountain to the level ground at the top of the mountain, and the height of the water column in the glass tube [increased], at this time, due to the maximum height, the outside atmospheric pressure was less than the closed air pressure in the bottle!

The pressure of the water on the bottom of the container [increases]. —p= gh - the maximum pressure of the bottle on the ground [unchanged] - the overall total mass does not change - the gravity does not change - the pressure does not change - the bottom area does not change - the pressure on the ground does not change!

The barometer is brought from the foot of the mountain to the level ground at the top of the mountain, and the height of the water column in the glass tube becomes larger, and the height increases, and the outside atmospheric pressure becomes smaller, so the external atmospheric pressure is less than the closed atmospheric pressure (atmospheric pressure) in the bottle!

The pressure of the water on the bottom of the container [increases]. —p= gh - h becomes larger, and the pressure on the bottom of the container increases.

The pressure of the bottle on the ground [unchanged] - the overall total mass does not change - the gravity does not change - the pressure does not change - the bottom area does not change - the pressure on the ground does not change.

The atmospheric pressure is much greater than the sum of the pressure of water on the test tube, so the test tube does not fall down, but rises.

It is to choose C, there is no gas on the top of the small test tube, there is no air pressure, and there is atmospheric pressure below, and the small test tube is pressed up.

There is no diagram case'Estimate option A

There's no picture.,Send it up.。

Actually, this is very understandable

1.The reason why the drink sealed in the bottle cannot be sucked out is because the atmospheric pressure outside the bottle is much greater than the atmospheric pressure inside the bottle, so the drink inside the bottle is squeezed by the atmospheric pressure outside, so the drink in the bottle cannot be sucked out.

2.In the Magdeburg hemispheric experiment, because the inside of the sphere is vacuum, the two hollow copper balls are tightly pressed together by the atmosphere. Thus, this experiment proves the existence of the force (atmospheric pressure) that holds the two balls tightly together, and the existence of atmospheric pressure.

As for Torricelli's experiment, the value of atmospheric pressure was measured for the first time by the height of the mercury pressed by atmospheric pressure (the specific steps are explained in detail in the book, if you don't understand, you can take a good look at lz).

The standard atmospheric pressure to the fifth power of the Pa represents the force to be experienced by the fifth-power Newtons from the atmosphere per square meter in the local area.

Hope it helps

lz must adopt the original mobile phone party is not easy).

The essence of drinking a drink is to suck the air out of the straw, and the pressure in the straw is less than the atmospheric pressure, and the atmospheric pressure will press the drink out of the bottle.

First of all, the Magdeburg hemisphere experiment is to pump the two hemispheres into a vacuum, so that the air pressure inside and outside the ball is unbalanced, and the outside atmospheric pressure compresses the two hemispheres tightly together, so it is difficult to separate the two hemispheres, so the existence of atmospheric pressure can be proved.

In the Torricelli experiment, the mercury column is inverted in the mercury tank, so the test tube is sealed, and the mercury column in the test tube will not fall, because of the presence of atmospheric pressure, the mercury column is propped up. The Torricelli experiment measured that the standard atmospheric pressure is the fifth power Pa, which can be expressed as 760mmHg, that is, from the formula p=f s, we can get p = kilogram cubic meter (density of mercury) Newton kilogram meter Newton square meter = Pascal.

Because the lower surface of the square iron block and the upper surface of the table are not completely smooth and cannot be completely touched together, the lower surface of the iron block still has atmospheric pressure, so it is only a balance of gravity and support. If, in a very ideal state, the lower surface of the square piece of iron and the upper surface of the table are very smooth (they can be perfectly attached), then the atmospheric pressure to which it is subjected will not be offset and it will be difficult to pick up. However, the general title will not give such a very ideal situation, so there is no need to consider this situation if it cannot be pasted together on the surface without special instructions.

(1) The length of the full scale of the syringe l, and the indication f of the spring dynamometer when the syringe piston just starts to slide

2) The atmospheric pressure at the summit of the mountain p=fl v

3) The height of Huaguo Mountain h=10(P0V-FL) δPV

A is right, B is wrong, no problem.

C is wrong. The air pressure above the potion increases. Because the total pressure of the potion and the air in the bottle should be equal to the atmospheric pressure, and the liquid medicine becomes less, the pressure of the gas will "increase".

Why is the total pressure between the potion and the air in the bottle equal to the atmospheric pressure? First of all, the total pressure cannot be greater than the atmospheric pressure, otherwise the potion will flow out of the air pipe, and if the total pressure is less than the atmospheric pressure, the air will flow in.

d is also wrong. d should be equal to, because the air pipe goes straight to the atmosphere, and the pressure is the atmospheric pressure.

Only A is right Let's put it this way, because there is no liquid medicine flowing out of the air pipe, that is to say, at the air pipe, the atmospheric pressure is balanced with the pressure in the medicine bottle, that is, the sum of the air pressure and water pressure above the liquid medicine is equal to the atmospheric pressure. And the potion is getting less and less, that is, the water pressure is decreasing, then the air pressure above the potion will be greater. However, this change in pressure is very small and equal to the change in the pressure of the potion.

The title does not explain whether it should be ignored or counted, and there are still some problems.

If you choose DC, because the liquid medicine flows downward, the volume of air in the bottle becomes larger, the pressure becomes smaller, and then the air flows in from the air pipe. d right.

Because there is an infusion tube and an air tube, the pressure inside the bottle is equal to the external pressure.

a.If the blood flows back into the infusion tube, the pressure in the bottle is too small, and the medicine bottle should be lowered.

b.Same as above, as long as the bottle does not move, the pressure remains the same. B false.

c Pair. d.Wrong.

C is right, the pressure in the air pipe is constant, otherwise it will not be able to enter the human body.

D is wrong, the air in the air duct is connected to the outside world and does not change.

d a, b is wrong, no problem. c is also wrong, the air pressure inside the bottle is varied. So choose D

The outside of the pressure cooker is subject to an atmospheric pressure. The pressure and atmospheric pressure of the gas-limiting pressure valve in the pressure cooker on the pressure-limiting outlet are p=n s+p0 (standard atmospheric pressure) = g s+p0=

If you find the pressure difference between the inside and outside of the pot, it is the pressure of the pressure limiting valve to the pressure-limiting outlet n s=g s=101859pa

Atmospheric pressure is the pressure generated by the weight of the upper atmosphere on objects on the surface of the earth.

Maximum pressure inside and outside, maximum pressure inside or maximum pressure difference between inside and outside?

The outside world is unchanged, the default is the standard atmospheric pressure p0, and the diameter of the pressure cooker is the interference term, because the gas can only do work on the pressure limiting valve Analysis of the pressure limiting valve (orientation is in the positive direction), because the pressure limiting valve is stationary, force = pressure x area.

0=(p-p0)*s (calculated from the diameter of the pressure-limiting outlet)-g (pressure of the pressure-limiting valve to the outlet).

Solve. In fact, whether the pressure calculation of junior high school or high school is relatively basic, atmospheric pressure is the same as hydraulics, the reason for the formation of the atmosphere is gravity, which can be imagined as a column of air acting on the object, the deeper reason is the continuous movement of gas molecules, countless impacts on the surface of the object, and the average value of the unit area per unit time of this impact force is the pressure, as long as this is understood, the pressure itself can be understood, as for the calculation, remember the formula on the basis of understanding (the formula also needs to be understood), Do some topics to familiarize yourself with, and junior high school pressure is very simple.

First of all, let's consider the principle of using a straw to absorb water: after the straw is sucked, the pressure inside the pipe is less than the air pressure outside the pipe, so the water is pressed up from the pipe. So it was concluded that *being able to suck water in is actually the result of the air pressure outside the tube being greater than the air pressure inside the tube* (which is the key to the problem).

With this conclusion, your problem will be solved: after inserting a smooth straw, the pressure in the tube will certainly become smaller, but after the liquid is inhaled at a certain height, the air pressure in the bottle will also become smaller (and the plug is so dead, the atmosphere cannot enter), so the air pressure outside the tube is not greater than the inside of the tube, and the water cannot be sucked up.

If you use an angular tube, you can ensure that the atmosphere can continue to enter the bottle, so that the air pressure outside the straw is greater than that inside the tube, and it is much easier to absorb water.