"Friction" Motion and Force PPT Courseware 3

Description

"Friction" Motion and Force PPT Courseware 3

learning target

1. Know how friction is generated;

2. Be able to explore and know the factors that affect the size of sliding friction;

3. Know the advantages and disadvantages of friction and understand the examples of friction in daily life;

4. It will increase beneficial friction or reduce harmful friction.

Give it a try

1. Press your palms firmly against the table and push forward, but keep your palms still relative to the table.

2. Press the palm of your hand lightly onto the table and push forward so that your palm slides relative to the table.

3． Use two fingers on the table to simulate walking and feel the direction of friction on the fingertips.

What kind of force do you feel friction is? Where does it work? What is the direction of action?

question:

1. What tool is used to measure friction? How to test?

A spring dynamometer pulls a wooden block at a constant speed. The pulling force is equal to the friction force.

2. How to change the pressure of the wood block?

Put weights on the block

3. How to change the roughness of the contact surface?

Place towels and cotton cloth on a long wooden board

4. What scientific methods are used?

Control variable method: When studying the effect of pressure on friction, control the roughness of the contact surface.

To study the effect of contact surface roughness on friction, control the pressure

Conversion method: The pulling force of the dynamometer on the object and the friction force on the object are a bunch of balancing forces, so the friction force is equal to the pulling force

2. Factors affecting the magnitude of sliding friction

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 magnitude of sliding friction is related to the roughness of the contact surface. The rougher the contact surface, the greater the sliding friction.

Choose your favorite two questions and show off your skills!

1. Fill in the blanks:

1. The amount of friction experienced by an object is related to ____ and _______ of the contact surface. An iron block weighing 90N is placed on a horizontal table. Xiaohong uses a horizontal pulling force of 30N to make it move in a straight line at a uniform speed to the right. , the friction force on the iron block is equal to ___N, and the direction is ___. If the pulling force becomes larger, the friction force _____ (fill in "increases", "unchanges" or "gets smaller").

2. In order to measure the friction force between a wooden block and the tabletop, Xiao Ming should use a spring dynamometer to pull the wooden block to do ____ motion in the horizontal direction on the tabletop. If the spring dynamometer indicates is 3.5N, then the friction force obtained experimentally is ____N. The principle used in the experiment is that the object moves ____ under the action of ____.

3. An object weighing 20N is pressed against a vertical wall with a force of 50N and remains stationary. The friction force on the object is _______N and the direction is _______.

4. The purpose of grinding the surface of sewing needles smooth is to _____; when braking suddenly, holding the brake handle tightly is to increase friction by _____ method; ball bearings are installed in the rotating parts of the machine, which can change ______ friction. To reduce friction by _____ friction.

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

File Info

Update Time: 2024-07-30

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

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