"Friction" Motion and Force PPT Download

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"Friction" Motion and Force PPT Download

Part One: Preview Perception

1. Sliding friction

1. Concept: When two objects in contact with each other slide relative to each other, a force is generated on the contact surface that hinders relative movement.

2. Cause: The two surfaces of objects in contact with each other are uneven.

3. The direction of friction: the relative motion or relative motion trend direction of the object _______.

4.Measurement:

(1) Tools: Spring dynamometer.

(2) Method: Use a spring dynamometer to pull the wooden block horizontally so that it moves in a straight line at a uniform speed along the long wooden board. The indication of the spring dynamometer is equal to the sliding friction force experienced by the wooden block.

2. Study the factors that affect the magnitude of sliding friction

1. Exploration method: Control variable method.

2. Research conclusion:

(1) The size of the sliding friction force is related to the pressure on the contact surface. The greater the pressure on the contact surface, the greater the sliding friction force.

(2) The size of the sliding friction force is also related to the roughness of the contact surface. The rougher the contact surface, the greater the sliding friction force.

3. Methods to increase and reduce friction

1. Methods to increase friction

(1) Increase the pressure.

(2) Increase the roughness of the contact surface.

(3) Use sliding instead of scrolling.

2. Methods to reduce friction

(1) Reduce the pressure.

(2) Reduce the roughness of the contact surface.

(3) Separate the contact surfaces.

(4) Use rolling instead of sliding.

Friction PPT, Part 2: Interactive Classroom Understanding

Methods to increase or decrease friction

The size of friction is related to the size of pressure and the roughness of the contact surface. Under the same conditions, rolling friction is much smaller than sliding friction. It can be seen that the methods to increase (or reduce) friction in production and life generally consider four aspects: (1) analyze whether the pressure changes; (2) analyze whether the roughness of the contact surface changes; (3) rolling and the transition between sliding; (4) Analyze whether the contact surface is separated.

[Example] During class cleaning, Xiaotian discovered that many phenomena are related to friction. Among them, the measures to reduce friction are ()

A. When cleaning the glass, press the rag tightly against the glass to wipe it.

B. The bookcase is equipped with rollers for easy movement.

C. The brush surface of the blackboard brush is made of rougher materials

D. The handle of the bucket is engraved with uneven patterns.

Analysis: When wiping the glass, press the rag tightly against the glass to increase the friction. A is wrong; there are rollers under the bookcase to facilitate moving positions, which changes sliding to rolling and reduces friction. B is correct; it is rougher to use. Materials with uneven patterns are used to increase friction by increasing the roughness of the contact surface. C and D are wrong; so choose B.

Answer B

Friction force PPT, part 3: try to apply

1. Friction

1. Regarding friction, which of the following statements is correct ()

A. There is always friction between rough objects that are pressed against each other.

B. An object may experience friction only when it is pressed against the surface of another object and has relative motion or relative motion tendency.

C. Two objects with relative motion must have friction.

D. An object at rest must have no friction

2. As shown in the figure, sliding friction is _______; static friction is _______; rolling friction is _______. (fill in serial number)

2. Explore the influencing factors of friction

3. The sliding friction force can be measured with a spring dynamometer. As shown in the picture, the block is pulled in the horizontal direction through the spring dynamometer to make the block move _______ (see the picture for the dynamometer indication). According to the knowledge of _______, the friction force between the block and the tabletop is _______.

4. In the experiment to explore the factors related to the magnitude of friction, three experiments using a spring dynamometer to pull an animal block at a uniform speed are shown in the figure. Comparing the two figures A and B, we can see that the magnitude of the friction force is related to _______; comparing the two figures _______, we can see that the magnitude of the friction force is also related to the roughness of the contact surface.

3. Methods to increase and reduce friction

5. Among the following practices, the one that reduces friction is ()

A. The soles and tires have uneven patterns.

B. When braking on a bicycle, hold the brake firmly

C. Form an air cushion between the bottom of the hovercraft and the water surface

D. In order to prevent the transmission belt from slipping, the belt needs to be tightened

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

"Friction" motion and force PPT teaching courseware:

"Friction" PPT teaching courseware on motion and force Part 1: Classification practice of knowledge points Knowledge point 1 Friction 1. Friction can be divided into _____ friction, ______ friction and ____ friction. Among them, sliding friction refers to: two objects in contact with each other..

"Friction" Motion and Force PPT:

"Friction" Motion and Force PPT Part One Content: Basic Knowledge Points Knowledge Point 1 Friction 1. The conditions for the generation of friction are that two objects are in contact with each other, have relative motion or have a tendency to move relative to each other. 2. As shown in the picture, use a spring dynamometer to pull the wooden block on the table.

"Two Force Balance" PPT teaching courseware on movement and force:

"Two Force Balance" PPT teaching courseware on motion and force Part 1: Classification practice of knowledge points Knowledge point 1 Judgment of equilibrium state 1. When an object is acted upon by several forces, if it remains in a _____ or ____________ state, we say that these forces _____ each other,...

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Update Time: 2024-11-22

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 2 industry PPT template

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