"The "Power" of Air" Pressure PPT Courseware

Description

"The "Power" of Air" Pressure PPT Courseware

learning target

1. Understand the causes of atmospheric pressure, be able to give examples of the existence of atmospheric pressure, and use atmospheric pressure to explain simple phenomena

2. Know the magnitude of Torricelli’s experiment and standard atmospheric pressure

3. Know that the atmospheric pressure can be measured with a barometer, and understand the relationship between atmospheric pressure and the decrease with height.

4. Inspire students’ interest in science and cultivate their sense of innovation through experimental exploration activities on the existence and measurement of atmospheric pressure.

Discussion and analysis

What inspiration did you get from the three experiments and what conclusions did you draw? Why does atmospheric pressure exist?

1. Atmospheric pressure: The earth is surrounded by a thick atmosphere. The pressure of the atmosphere on objects immersed in it is called atmospheric pressure, or atmospheric pressure or air pressure for short.

2. Cause: Able to flow (generate pressure in all directions) due to gravity

Measurement of atmospheric pressure

Torricelli experiment:

Want to know about the world's first experiment to accurately measure atmospheric pressure?

⑴ During the experimental operation, why is it necessary to fill the tube with mercury and then block the mouth of the tube and place it upside down in the mercury tank?

⑵ After letting go, the mercury column in the tube drops. Is there air above the mercury surface in the tube?

Is there atmospheric pressure above the mercury level in the tube?

⑶What pressure is exerted on the liquid surface of the mercury tank outside the tube?

⑷Who exerts the pressure on the lower part of the tube that is parallel to the mercury tank?

⑸What is the relationship between the pressure of a 760 mm mercury column and atmospheric pressure?

The size of the atmospheric pressure measured by Torricelli's experiment is called a standard atmosphere.

P0=Pmercury=ρgh

=13.6×103kg/m3×9.8N/kg×0.76m

=1.013 ×105Pa

Such a large pressure: 1.013×105Pa is equivalent to a pressure of about 10N per square centimeter.

The relationship between boiling point and air pressure

As the air pressure increases, the boiling point of water increases; as the air pressure inside the bottle decreases, the boiling point of water decreases.

In the above experiment, the same results can be obtained with other liquids.

It shows that the boiling point of all liquids increases as the air pressure increases and decreases as the air pressure decreases.

The atmospheric pressure was so strong, why didn't the house collapse?

Because there is atmosphere inside the house, the pressure from the atmosphere inside and outside the house is equal and opposite, so the house will not collapse.

Class exercises

1. The famous experiment to determine the value of atmospheric pressure is the ________ experiment. The value of atmospheric pressure is approximately ________ Pascal.

2. In the experiment to measure the atmospheric pressure value, the thickness of the glass tube used and the measurement result _________, it should be placed vertically during the experiment. If the glass tube is tilted, the length of the mercury column in the tube will be _______, and the vertical height of the mercury column will be ________.

3. If water is used to perform the Torricelli experiment, there is a vacuum above the tube, and the atmospheric pressure can support a water column about _______ meters high.

4. A student accidentally mixed a small amount of air into the glass tube while doing the Torricelli experiment, and the measurement result will be ( )

A. Too big B. Too small c. equal D. It's possible

5. There is a clothes hook made of plastic or rubber with an empty "leather bowl" in the middle. You can press it on a smooth wall or glass and hang a few more clothes on the hook without falling off. ,This is because( )

A. The wall has suction to it B. The glass has suction to it

C. The clothes nails have adhesion to the wall or glass D. The effect of atmospheric pressure

6. When doing the Torricelli experiment, the height difference between the inside and outside of the tube was measured to be 76cm. If mercury is added to the tank to raise the mercury level by 1cm, the height difference between the inside and outside of the tube is ( )

A.76cm B.75cm C.77cm D.80cm

Class summary

1. Atmospheric pressure: There is pressure inside the air in all directions. This pressure is called atmospheric pressure.

2. Causes of atmospheric pressure: Gas is fluid and affected by gravity

3. Experiment to prove the existence of atmospheric pressure: Magdeburg Hemisphere Experiment

4. Experiment to measure atmospheric pressure: Torricelli experiment

5. The value of atmospheric pressure: one standard atmospheric pressure = 760mm mercury = 1.013 × 105pa, which is approximately equal to 105pa

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For more information about the "The Power of Pressure Air" PPT courseware, please click the "Pressure ppt The Power of Air ppt" tag.

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Update Time: 2024-10-20

This template belongs to Physics courseware Shanghai Science Edition 8th Grade Physics industry PPT template

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