"Internal Energy" Mechanical energy, internal energy and its transformation PPT courseware

Description

"Internal Energy" Mechanical energy, internal energy and its transformation PPT courseware

learning target

1. Know that matter is composed of a large number of molecules.

2. Know that the molecules of all substances are constantly undergoing irregular motion and molecular thermal motion.

3. Know that there are interactions between molecules.

4. Be able to identify diffusion phenomena and explain them from the perspective of molecular kinetic theory.

5. Know that the higher the temperature of an object, the more intense the thermal motion of molecules.

1. Basic image of material structure

1. Objects are composed of a large number of molecules

A molecule is the size of an apple as a human is is the size of the earth.

Common substances are composed of a large number of molecules

2. Molecules are constantly moving irregularly

What can we discover by observing the above phenomena?

diffusion phenomenon

Definition: Two different substances can spontaneously enter each other. This phenomenon is called diffusion.

According to the phenomenon of diffusion, we can conclude that the molecular formula is moving.

By observing the above phenomena, think about the relationship between the speed of molecular motion and temperature?

Experimental results

The molecules that make up matter are in constant, irregular motion. The higher the temperature, the more intense the movement of molecules. We call this motion thermal motion.

3. There are interactions between molecules

The image on the right shows the attraction between molecules.

When compressing an object, force is required, indicating that there is also a repulsive force between molecules.

2. Characteristics of solids, liquids and gases

Knowledge summary

Whether it is a solid, liquid or gas, the state of molecular motion is related to temperature. As the temperature increases, the movement of molecules becomes intense, the distance between molecules becomes larger, and the volume of objects generally expands.

Summary of this lesson

1. Matter is composed of molecules.

2. The diffusion phenomenon shows:

(1) The molecules of all objects are constantly moving irregularly (thermal motion).

(2) There are gaps between molecules.

3. There are attraction and repulsion forces that interact between molecules.

Practice in class

1. Among the following phenomena, which one can show that the molecules of an object are constantly moving ( )

A. There are many small insects moving around in the dirty water without any pattern.

B. Put mothballs in the suitcase. After a while, the clothes will smell like camphor.

C. When the classroom was being cleaned, dust was flying all over the room.

D. Washed wet clothes will dry out after a while

2. The following phenomenon shows that there is repulsion between molecules ( )

A. Coal has been piled in the corner for a long time, and the inside of the wall has turned black.

B. After opening the vinegar bottle, I quickly smelled the vinegar smell.

C. If you press the bread with your hands, the volume of the bread will become smaller.

D. Liquid enclosed in a container is difficult to compress

3. Put two pieces of smooth dry glass together and it is easy to separate them, but if you sprinkle some water on the glass and then put them together, it will be difficult to separate them. This phenomenon explains ( )

A. There is no force between solid molecules, but there is force between liquid molecules.

B. There is no force between molecules of the same kind, but there is force between molecules of different kinds.

C. There is a force between any molecules. The smaller the distance, the greater the force.

D. Water is viscous, and whether there are forces between molecules has nothing to do with it.

4. Smoking is harmful to health. The International Health Organization has stipulated the "World Smoking Smoking Day", and signs of smoke-free places can be seen everywhere. Because when one person smokes in a public place, other people will also "passively smoke". We use molecular kinetic theory to explain the reasons for this result.

Answer: Gas molecules are constantly moving irregularly, and they can reach the space they can reach.

5. In the building materials market, there is a plate-shaped or block-shaped material made of sawdust. It is made by adding adhesive to the binder to make the distance between the binder and binder molecules close to the mutual attraction range, and then suppressing it. Yes, which point of view of molecular kinetic theory is used in this manufacturing method?

Answer: There are also interactions between molecules using different substances.

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For more information about the PPT courseware "Mechanical Energy Internal Energy and Its Transformation into Internal Energy", please click the Mechanical Energy Internal Energy and Its Transformation ppt Internal Energy ppt tag.

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Update Time: 2024-10-02

This template belongs to Physics courseware Beijing Normal University Ninth Grade Physics Volume 1 industry PPT template

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