"Atmospheric Pressure" PPT courseware

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"Atmospheric Pressure" PPT courseware

Part One: Practice:

1. If mercury is replaced by water, calculate how high the water column can be held up by atmospheric pressure?

2. Immerse the measuring cylinder filled with water with the mouth facing downwards in the water. Grasp the bottom of the cylinder and slowly lift it up until the opening does not leave the water. Then the inside of the measuring cylinder ( )

A is still full of water

There is still water in B, but it is not full. The water surface inside the tube is higher than the water surface outside the tube.

C There is still water, but it is not full. The water level inside the tube is lower than the water level outside the tube.

The upper part of D is vacuum and the pressure is zero

Atmospheric Pressure PPT, Part 2: Application of Atmospheric Pressure

(1) Vacuum compression storage bag;

Vacuum packaging of food and items can save space, and can also prevent mildew, moth, bacteria, moisture, etc.

The relationship between atmospheric pressure and weather

1. At the same altitude, the atmospheric pressure in different areas is not necessarily the same;

2. The atmospheric pressure in the same area at different times is not necessarily the same;

The relationship between atmospheric pressure and weather

High pressure area: an area with high air pressure at the same height

Low pressure area An area with low air pressure at the same altitude

What are the characteristics of the airflow directions in high-pressure and low-pressure areas?

what's the weather like?

Atmospheric pressure PPT, part 3: influence of atmospheric pressure

Effect of atmospheric pressure on human body

Thinking: The atmosphere can produce such great pressure, but why are people living in the atmosphere okay?

Activity: If you suck the skin on the inside of your arm with your mouth for a period of time, what will happen?

There is also air pressure inside the human body. Under normal circumstances, the internal and external atmospheric pressure is balanced.

Effect of atmospheric pressure on boiling point of liquids

Some mountaineers discovered when climbing Mount Everest that even if the water had been boiling for a long time, the rice in the pot still could not be cooked. Later, a thermometer was used to measure the temperature of the boiling water, which was only about 85°C.

Activity: Explore the relationship between the boiling point of water and air pressure.

in conclusion:

1. The boiling point of a liquid is related to the air pressure.

As air pressure increases, boiling point increases

The pressure decreases and the boiling point decreases

2. The boiling point of a liquid is not fixed.

Application: pressure cooker

Atmospheric pressure PPT, part 4: Principle of pressure cooker:

Utilizing the principle that the boiling point of liquid increases with the increase of air pressure, the gas pressure is close to 2 atmospheres during operation, and the boiling point of water is close to 120ºC, which can increase the cooking speed and save fuel.

Note: There are relatively strict requirements for the use of pressure cookers. If the operating requirements are violated, it may easily cause danger.

1. The water vapor in the pressure cooker cannot escape before opening the pressure limiting valve, which will increase the air pressure in the pot and increase the boiling point of water.

2. When the pressure of the gas in the pot on the pressure limiting valve is equal to the gravity of the pressure limiting valve plus the force of the outside atmospheric pressure on the pressure limiting valve, it is cooked.

3. When the pressure of the gas in the pot on the pressure-limiting valve is greater than the gravity of the pressure-limiting valve plus the force of the outside atmospheric pressure on the pressure-limiting valve, it will explode.

Atmospheric pressure PPT, Part 5 content: Class summary:

1. The influence of atmospheric pressure on weather

High pressure area, air moves from top to bottom, and the weather is clear and dry

Low pressure area, air moves from bottom to top, the weather is rainy and humid

2. The effect of atmospheric pressure on the boiling point of liquids

The greater the pressure, the higher the boiling point of the liquid

The lower the air pressure, the lower the boiling point of the liquid

Atmospheric pressure PPT, part 6 content: A quick test:

1. Which of the following statements is incorrect ( )

A Generally, atmospheric pressure decreases with increasing altitude.

B Generally, high pressure areas have sunny and dry weather

C airflow flows upward to form a high pressure area

D airflow flows downward to form a high pressure area

2. When beef is cooked in a pressure cooker, the beef will easily rot. The reason is ()

(A) The pressure of the pressure cooker is too high and the beef is crushed.

(B) The water temperature in the pressure cooker is high, and the beef is easily cooked at high temperatures.

(C) The pressure in the pressure cooker is high and the beef will easily swell and cook.

(D) None of the above statements are correct

3. In an experiment to observe the boiling of water, the thermometer used was accurate, and the observed temperature of water boiling was 97°C. The possible reason for this is ( )

There is too much water in container A

BThe heating power is not weak

CThe local atmospheric pressure is greater than 1 standard atmosphere

DThe local atmospheric pressure is less than 1 standard atmosphere

Keywords: Zhejiang Education Edition eighth grade science PPT courseware free download, atmospheric pressure PPT download, .PPT format;

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Update Time: 2024-11-24

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