Cours PPT « Force et mouvement de frottement » 2

描述

Cours PPT « Force et mouvement de frottement » 2

friction dans la vie

1. Lorsque vous écrivez avec un crayon, la friction entre la pointe du crayon et le papier

2. Lors de l'aiguisation d'un crayon avec un couteau, la friction entre le crayon et le couteau

3. Lorsque la main glisse sur la table, le frottement entre la main et la table

4. Lors de l'effacement du tableau noir avec une gomme pour tableau noir, la friction entre la gomme pour tableau noir et le tableau noir

5. Poussez et tirez la table au sol.

6. Frottement entre les semelles et la chaussée lors de la marche.

7. Frottement entre la main et l’objet lors de la prise de quelque chose.

Lorsque deux objets en contact l'un avec l'autre se déplacent l'un par rapport à l'autre, la force produite par la surface de contact qui entrave le mouvement relatif des objets est appelée frottement statique.

Si la bibliothèque ne peut pas être poussée, pensez-vous qu’il y a une friction entre la bibliothèque et le sol ?

1. Qu'est-ce que le frottement ?

Lorsque deux objets en contact ou en contact l'un avec l'autre se déplacent l'un par rapport à l'autre ou ont tendance à se déplacer l'un par rapport à l'autre, une force qui entrave le mouvement relatif est générée sur la surface de contact. Cette force est appelée frottement.

think:

1: What are the conditions for friction to occur?

Two objects contact and squeeze each other, move relative to each other, or have a tendency to move relative to each other

2: The direction of friction?

Parallel to the contact surface and opposite to the direction of relative motion

What does the magnitude of sliding friction depend on?

Conjecture: 1. The pressure on the contact surface

2. Roughness of the contact surface

3.…

Basis for guessing: When you push a box, the heavier the box, the harder it is to push; the rougher the ground, the harder it is to push.

equipment:

Design experiment: wooden board, wooden block, spring dynamometer, hook code, towel

Principle: Conditions for balance of two forces

1. How to change the pressure on the contact surface?

Put hook codes on wooden blocks

2. What tool is used to measure the friction force? How to test?

Spring dynamometer pulls the wooden block at a constant speed, the pulling force is equal to the friction force

3. What scientific methods are used?

Control Variable

think:

1. What phenomena exist in daily life?

2. Which of these frictions are beneficial? Which ones are harmful?

3. Can you talk about how to increase beneficial friction? How to reduce harmful friction?

Ways to increase and decrease friction:

1. Increase friction

(1) Increase pressure

(2) Increase the roughness of the contact surface

2. Reduce friction

(1) Reduce pressure

(2) Reduce the roughness of the contact surface

(3) Change sliding to scrolling

(4) Use methods such as adding lubricating oil to make the two friction surfaces in contact with each other smooth.

Friction

1. Friction: When two objects in contact with each other move relative to each other, a force will be generated on the contact surface that hinders relative movement. This force is called friction (f).

2. Factors affecting the magnitude of sliding friction

Amount of pressure

The roughness of the contact surface

3. Methods to increase friction

Increase the pressure. For example: when braking, increasing pressure is used to increase friction.

Increase the roughness of the contact surface. For example, there are uneven patterns on the soles and tires.

4. Methods to reduce friction

Reduce stress

Reduce the roughness of the contact surface

Use scrolling instead of sliding

Keep the friction surfaces of the two contact surfaces away from each other

Add lubricant

The electromagnetic field separates the contact surfaces

Use air cushion

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For more information about the "Friction Force and Motion" PPT courseware, please click the Friction ppt Force and Motion ppt tag.

"Friction" interaction PPT download:

"Friction" Interaction PPT Download Part One Content: [Learning Literacy and Objectives] Physical concepts: 1. Understand the conditions and directions of sliding friction and the factors that affect its magnitude, and master the formula for calculating sliding friction. 2. Understand Conditions for the generation of static friction..

"Friction" interaction PPT courseware:

"Friction" Interaction PPT Courseware Part One: Course Standard Requirements 1. Know the conditions under which sliding friction occurs, and be able to determine its direction and solve for its magnitude..

"Friction" interaction PPT:

"Friction" Interaction PPT Part One Content: Learning Objectives 1. Know the conditions under which sliding friction occurs, and be able to determine its direction and solve for the magnitude of sliding friction. 2. Knowing the conditions under which static friction occurs, you can determine its direction and solve for the magnitude of static friction.

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更新时间: 2024-11-21

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