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

Description

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

learning target

1. Understand the concept of internal energy and know the unit of internal energy - Joule.

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 smaller the internal energy.

3. Know that work and heat transfer can change the internal energy of an object.

4． Understand internal energy through analogy to mechanical energy and understand the analogy method.

Core test points: methods of changing internal energy; heat transfer and work.

Preview before class

1. The sum of the thermal motion _______ and _______ of all molecules in an object is called the internal energy of the object; the internal energy of the same object is related to the _______ of the object.

2. The internal energy of an object can be changed through _______ and _______.

3In the process of heat transfer, the energy transferred is always expressed as ( )

A. An object with large internal energy is transferred to an object with small internal energy.

B. An object with a large mass is transferred to an object with a small mass

C. Objects with high temperature are transferred to objects with low temperature

D. Objects with high density are transferred to objects with low density

4． Among the following examples, the internal energy of an object increases due to work done ()

A． In summer, people feel very hot under the sun

B． When cutting a wooden board with a saw, the saw blade gets hot

C. Steam rice with high temperature steam

D. Use hot water heaters to increase room temperature in winter

Lectures in class

Knowledge point 1. Internal energy

(1) Molecular kinetic energy

Molecules are constantly making irregular thermal motions. Like all moving objects, moving molecules also have kinetic energy. The higher the temperature of an object, the faster the molecules move and the greater their kinetic energy.

The energy possessed by the irregular thermal motion of molecules in an object is called molecular kinetic energy.

(2) Molecular potential energy

Because there is a certain distance between molecules and a certain force, the molecules have potential energy, which is called molecular potential energy.

(3) Internal energy of the object

The sum of the molecular kinetic energy and molecular potential energy of all the thermal motion of molecules inside an object is called the internal energy of the object.

[Example 1] (2014·Benxi) Which of the following statements about internal energy is correct ( )

A． Objects with a temperature below 0°C have no internal energy

B． If the temperature inside an object increases, it will definitely increase

C. The increase in energy in an object must be due to the absorption of heat

D. As the temperature of an object increases, the internal energy will increase

[Exercise 1] Regarding internal energy, which of the following statements is correct ( )

A． Hot objects have internal energy, cold objects have no internal energy

B． Neither moving nor stationary objects have internal energy

C. Only liquids have internal energy, while neither solids nor gases have internal energy.

D. Any object has internal energy in any state

Knowledge point 2. Methods to change the internal energy of an object

(1) Heat transfer

①The conditions for heat transfer: there is a temperature difference between objects; ②The essence of heat transfer: internal energy is transferred between different objects or between different parts of the same object; ③The direction of heat transfer: heat transfers from a high-temperature object (or a high-temperature object) part) to the low-temperature object (or the low-temperature part of the object). During the heat transfer process, the high-temperature object releases heat and its internal energy decreases; the low-temperature object absorbs heat and its internal energy increases; ④ The final result of heat transfer: If the heat transfer process ends , the temperature becomes the same. If there is no energy loss, the reduced internal energy of the high-temperature object is equal to the increased internal energy of the low-temperature object.

(2) Do work

Doing work changes the internal energy of an object. When work is done on the object, the internal energy of the object increases; when work is done on the object externally, the internal energy of the object decreases. The essence of doing work to change the internal energy of an object is the mutual conversion between internal energy and mechanical energy. When doing work on an object, the mechanical energy is converted into internal energy, which increases the internal energy of the object; when the object does work on the outside, the internal energy of the object is converted into mechanical energy, which increases the internal energy of the object. reduce.

(3) Work and heat transfer are equivalent in changing the internal energy of an object.

When an object's internal energy increases, it may be because the outside world has done work on it, or it may have absorbed heat; when an object's internal energy decreases, it may be because it has done work on the outside world, or it may have released heat.

In-class testing

1. (2014•Guilin) ​​Regarding the internal energy of objects, which of the following statements is wrong ( )

A． The internal energy of an object cannot be changed

B． Heat transfer can change the internal energy of an object

C. Work can change the internal energy of an object

D. Internal energy is the sum of the kinetic energy and potential energy of all molecules in an object

2. (2014·Zhangzhou) In the following way, the internal energy of an object is increased by doing work ( )

A． Rub hands to keep warm B. Keep warm by fire C. Hot water bottle for heating D. "Blow" into your hands to warm them

3. (2014•Huangshi) Among the following examples, the internal energy of an object is changed through heat transfer ( )

A． Rubbing your hands together for a while outdoors in winter will make you feel warm

B． Bending the wire repeatedly will cause the bend to become hot.

C. A child slides down the slide and feels a burning sensation in his buttocks

D. People use hot water bottles to keep warm in winter

Keywords: Internal energy and heat engine teaching courseware, understanding of internal energy teaching courseware, Guangdong and Shanghai version ninth grade physics PPT courseware download, ninth grade physics slide courseware download, internal energy and heat engine PPT courseware download, understanding of internal energy PPT courseware download, .PPT format;

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 3:

"Understanding Internal Energy" Internal Energy and Heat Engine PPT Courseware 3 Knowledge Review Concepts of Kinetic Energy and Potential Energy The energy an object has 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 has due to elastic deformation is called Elastic potential energy. point..

"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...

File Info

Update Time: 2024-10-05

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

Preview