"Understanding Internal Energy" Internal Energy and Heat Engine PPT Courseware 3

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"Understanding Internal Energy" Internal Energy and Heat Engine PPT Courseware 3

Knowledge review

The concept of kinetic energy and potential energy

The energy an object possesses due to motion is called kinetic energy;

The energy an object has due to being lifted up is called gravitational potential energy

The energy an object possesses due to elastic deformation is called elastic potential energy.

Preliminary knowledge of molecular kinetic theory

Objects are made up of a large number of molecules

Molecules are constantly making irregular movements

There are interaction forces between molecules.

1. Internal energy

1. Molecules have kinetic and potential energy

①The moving basketball has kinetic energy

Conclusion: Moving molecules also have kinetic energy.

The energy possessed by molecules due to their irregular motion is called molecular kinetic energy.

②The stone and the earth attract each other and have potential energy

Do molecules that attract each other also have potential energy?

Conclusion: Molecules that attract each other also have potential energy

2. internal energy of object

The sum of the kinetic energy of thermal motion and the potential energy of molecules of all the molecules that make up an object is called the internal energy of the object.

The unit of internal energy is Joule (J)

Mechanical energy is related to the mechanical motion of the entire object, and internal energy is related to the thermal motion of the molecules inside the object and the interaction between molecules, so internal energy is another form of energy different from mechanical energy.

Because the molecules of all objects are constantly moving irregularly, all objects have internal energy.

2. Changes in the internal energy of an object

(1) Heat transfer:

1. Direction: high temperature - low temperature

2. Condition: temperature difference

3. Termination: The temperature is consistent

4.Essence: transfer of internal energy

2. How to change the internal energy of an object

(1) Heat transfer can change internal energy

When heat transfer occurs, the energy in a high-temperature object decreases and the energy in a low-temperature object increases.

The internal energy of an object increases when it absorbs heat and decreases when it releases heat.

The more heat it absorbs or releases, the greater its internal energy changes.

The nature of heat transfer:

Internal energy is transferred from one object to another.

(2) Doing work can change internal energy

small experiment

As shown in Figure 1, a small ball of cotton dipped in ether is placed in a thick glass tube equipped with a piston. What will happen when the piston is pressed down quickly? Why?

Cotton can catch fire.

Because the piston does work to compress the air, the internal energy of the air increases and the temperature rises, reaching the ignition point of ether, causing the cotton to burn.

There is some water in a large-mouth glass bottle, and there is water vapor above the water. Inflate the bottle. When the cork jumps up, observe what changes happen inside the bottle? Why?

When the cork jumps up, white mist appears inside the bottle.

When the cork jumps up, the air pushes the cork to do work on the cork. The internal energy decreases, the temperature decreases, and the water vapor in the air liquefies when it is cooled.

practice

1. The ways to change the internal energy of an object are ________ and ________.

2. The sum of ____________________ and ____________________ inside an object is called the internal energy of the object. As the temperature of an object increases, ____________________ must increase, so the internal energy of this object _________.

3. In winter, if you breathe into your hands with your mouth, your hands will warm. This is to increase the internal energy of your hands in a _________ way, and its essence is that the internal energy is _________ between objects. Rubbing your hands can also warm your hands. , this is to increase the internal energy of the hand using _______________. In this process, _______________ energy is converted into internal energy.

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For more information about the PPT courseware "Internal Energy and Heat Engines to Understand Internal Energy", please click the Internal Energy and Heat Engines ppt to Understand Internal Energy ppt tag.

"Understanding Internal Energy" Internal Energy and Heat Engine PPT Courseware 2:

"Understanding Internal Energy" Internal Energy and Heat Engine PPT Courseware 2 Learning objectives of this lesson 1. Know the concept of internal energy and the units of internal energy; 2. Be able to simply describe the relationship between temperature and internal energy; 3. Know and experience changes in internal energy Two methods of energy The knowledge object of molecular kinetic theory is...

"Understanding Internal Energy" Internal Energy and Heat Engine PPT Courseware:

"Understanding Internal Energy" Internal Energy and Heat Engine PPT Courseware Learning Objectives 1. Understand the concept of internal energy and know the unit of internal energy, joules. 2. Can simply describe the relationship between temperature and internal energy, knowing that for the same object, the higher the temperature, the greater the internal energy, and the lower the temperature, the greater the internal energy..

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Update Time: 2024-07-30

This template belongs to Physics courseware Guangdong and Shanghai Edition Ninth Grade Physics Volume 1 industry PPT template

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