"Sliding and Rolling" Motion and Force PPT

Description

"Sliding and Rolling" Motion and Force PPT

Part One Content: Exploration Activities

Two ways in which objects move

An object moves on the surface of another object in two ways: sliding and rolling.

slide scroll

(1) Measuring the friction force of sliding and rolling objects

Experiment name: Explore the friction between sliding and rolling

Experimental equipment: trolley, spring dynamometer, weights

Changing conditions How the wheel moves

The constant conditions are the weight of the trolley and the smoothness of the contact surface.

experimental method

Use a car to do comparative experiments. Add some weights to the car so that it is easier to measure the value of friction.

Summary: The amount of friction is related to the movement mode of the object (sliding or rolling). For the same object, the friction of rolling is small and the friction of sliding is large. The friction force when an object rolls on another object is only about 1/20 or less than when it slides.

discuss:

⊙Why does a stationary car require a certain amount of pulling force to move? Why does a moving car stop slowly when it loses power?

⊙The brakes of cars and bicycles are used to prevent the wheels from turning. Why can the car stop quickly when the wheels stop turning?

(2) Understanding and making ball bearings

A ball bearing is a device that converts sliding into rolling

Sliding and scrolling PPT, part 2: expansion and extension

What are the examples of sliding friction and rolling friction in life?

Sliding friction: sliding on slides, erasing blackboards, writing with pens, wheels when braking, etc.

Rolling friction: ballpoint pen writing, running wheels, pulley wheels, etc.

In daily life and production, what designs are designed to increase friction? Which designs are designed to reduce friction?

Increase friction: patterns on wheels and soles, brakes, spikes for running, tracks on tank wheels, etc.;

Reduce friction: Lubricate bicycle axles, coat inflexible zippers with paraffin, ball bearings, etc.

Sliding and scrolling PPT, Part 3: Class summary

There are two modes of motion due to friction: rolling and sliding. Sliding has greater friction than rolling; roller bearings are a device that converts sliding into rolling. Sliding and scrolling have many applications in life.

Sliding and scrolling PPT, Part 4: Classroom training

1. Fill in the blanks

1. The size of the friction force is related to the movement mode of the object. For the same object, the friction force of rolling ( ) and the friction force of sliding ( ).

2. A moving object will stop after losing power because of the action of ( ).

2. Choice

1. In an experiment to measure the sliding and rolling friction of an object, the changing conditions are ( )

A. The weight of the car B. The smoothness of the contact surface C. The movement mode of the wheel

2. The object can move when subjected to a certain amount of force and stop slowly due to the action of ( ).

A. Friction B. Pull C. Gravity

Sliding and scrolling PPT, Part 5: Homework

Improve the production of ball bearings and exchange production experiences with each other.

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For more information about the "Motion and Force Sliding and Rolling" PPT courseware, please click the Motion and Force ppt Sliding and Rolling ppt tab.

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Update Time: 2024-10-02

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