"Atmospheric Pressure" PPT

Description

"Atmospheric Pressure" PPT

Part One Content: Classroom Experiment

experiment one

Demonstration of the "Cover Cup" Experiment

1. Place a piece of cardboard flat on the mouth of a flat glass, hold it down with your hand, and turn it upside down. What will happen after you let go?

discuss

1. Why put a piece of cardboard on the rim of an empty glass, turn the device upside down, and find the piece of cardboard falling?

Because there is air inside the cup and air outside the cup, the upward and downward pressure on the paper will cancel out and the paper will fall due to its own gravity.

2. Fill the glass with water, cover the mouth of the glass with a piece of cardboard, hold it with your hand, and turn it upside down. What will happen after you let go?

The cardboard did not fall off and the water did not flow out.

2. Fill the glass with water, cover the mouth of the glass with a piece of cardboard without leaving any air, hold the piece of paper, and turn the glass upside down so that the water does not flow out and the piece of paper does not fall. why is that?

Due to the effect of atmospheric pressure, it is the atmospheric pressure that holds the water and cardboard in the cup

Experiment 2

Changes to milk cartons?

Why does this happen?

The paper packaging drink box was originally filled with

drink, after the drink is sucked out, the drink

The pressure inside the box decreases and the external pressure becomes stronger.

As a result, the drink box was deflated by the outside atmospheric pressure.

Atmospheric pressure PPT, part 2: thinking and discussion

1. As shown in Figure 2-14, why can the drink in the cup enter the mouth through the straw?

When a person uses a straw, he first inhales the gas in the tube into his body, causing the air pressure in the tube to drop. The drink at the lower end is forced into the tube by the outside atmospheric pressure, and the person can drink the drink.

2. As shown in Figure 2-15, why can the suction cup with a hook stick firmly to the surface of the ceramic tile?

After the gas in the soft rubber disc of the suction cup hook is squeezed out, the air pressure in the disc is less than the outside air pressure. Therefore, the outside atmosphere tightly presses the suction cup on the object.

Why doesn't the liquid in the dropper drip?

The air pressure inside the dropper is less than the outside atmospheric pressure, and the outside atmospheric pressure holds the liquid

Atmospheric pressure PPT, the third part: the size of atmospheric pressure

1. Measuring tools: empty box barometer, mercury barometer

How big is the atmospheric pressure?

The origin of the mercury barometer:

Activity: Invert the mineral water filled with water into the sink. What will you see?

If there is no bottom to block the water column in the bottle and the water column in the bottle is allowed to rise freely, can you guess how high the water column can rise?

2. The size of atmospheric pressure:

1 standard atmosphere

=760 mm of mercury

=76 centimeters of mercury

=1.01×105Pa

＝10.3 meters water column

The size of standard atmospheric pressure:

Atmospheric pressure measured near sea level

1.01 × 105 Pa = 760 mm of mercury (1 mm of mercury ≈ 133 Pa)

Thinking: During the National Day, classmate Xiao Ming and his parents drove from Yongjia Shangtang to Hangzhou along the Zhuyong Expressway. When they drove to high places, they felt discomfort in their ears. What is going on?

Atmospheric pressure PPT, Part 4: Consolidation exercises:

1. Xiaojiang wants to use empty cans to experience the existence of atmospheric pressure. The following operations can achieve the purpose: ( )

A. If you squeeze the can with your hands, the can will become flat.

B. Use a syringe to extract the air from the sealed can, causing the can to become deflated

C. Let the can fall from a high place and the can will become flat.

D． Place sealed cans in deep water and the cans will become deflated

2. Someone sucked the air out of a small empty bottle with his mouth, and the bottle immediately hung on his lips. The main reason is ( )

A. Suck the bottle with your mouth

B. The result of the action of the remaining air in the bottle

C. The saliva on the side of the mouth sticks to the bottle

D. Press the vial against your lips with atmospheric pressure

3. As shown in the picture, you can suck the drink from the can into your mouth with a straw. This is because ( )

A. The role of people's attraction to drinks

B. The straw itself has the function of sucking drinks

C. The effect of atmospheric pressure on the liquid surface

D． The effect of liquid pressure

Atmospheric Pressure PPT, Part 5: Class Summary

1. The existence of atmospheric pressure

1. The atmosphere exerts pressure on objects in it, and atmospheric pressure exists in all directions.

2. Magdeburg Hemisphere Experiment

①The existence of atmospheric pressure

②The value of atmospheric pressure is very large

2. The size of atmospheric pressure

1. Measuring tools: barometer (empty box, mercury)

2. Unit: 1 mm of mercury = 133 Pa

3. Change pattern: The higher it is from the ground, the smaller the atmospheric pressure value is.

4. 1 standard atmosphere = 1.01×105 Pa = 760 mmHg

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Update Time: 2024-07-04

This template belongs to science courseware Zhejiang Education Edition Eighth Grade Science Volume 1 industry PPT template

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