"Pulley" Mechanical and Work PPT Courseware 2

Description

"Pulley" Mechanical and Work PPT Courseware 2

Review questions:

What is leverage?

What are the five elements of leverage?

How to draw a muscle arm? Step by step instructions?

What is the principle of leverage balancing?

Classification of leverage? What is the relationship between various lever arms?

1. Get to know pulleys

1. What is a pulley?

A pulley is a wheel that has grooves around it and can rotate around an axis.

2. Classification of pulleys:

According to the movement state of the pulley, it can be divided into: fixed pulley and movable pulley

A. Fixed pulley

Name: A pulley whose position is fixed when in use.

B. moving pulley

Name: When in use, the position of the pulley moves together with the pulled object.

in conclusion:

1. Fixed pulley:

(1) The direction of force can be changed.

(2) Effortless.

(3) No need to save or waste distance.

(4) Essence: L1＝L2, equal-arm lever, F1＝F2

2. Moving pulley:

(1) Does not change the direction of the force.

(2) Save half the effort.

(3) Move more distance

(4) Essence: L1=2L2, the power arm is the resistance arm two

times the leverage F1=1/2F2,

Thought questions:

1: The advantage of using a fixed pulley is ＿＿＿.

2: The advantage of using a movable pulley is ＿＿＿.

Can we use the advantages of fixed pulleys and movable pulleys to combine them to make them labor-saving and convenient?

able. Combine them into a pulley block.

1: Pulley block consists of a fixed pulley and a movable pulley.

Experimental results: The magnitude of the pulling force F is related to the number n of the rope strands used to lift the movable pulley.

2: Pulley block

Experiments have shown that when a pulley block is used to pull a heavy object, if the weight and friction of the movable pulley are ignored and the movable pulley is pulled by several strands of rope, the force used is a fraction of the friction between the object and the contact surface. That is, F=1/n f

1. There are ______ types of pulleys. The shaft of the pulley is fixed when used, which is called ______. The position of the pulley moves together with the pulled object when used, which is called ______.

2. Using _____ pulleys cannot save effort, but it can change __________; using ____ pulleys can save half the effort, but it cannot change __________.

3. From the perspective of the length of the lever's arm, the fixed pulley is actually the _________ lever, while the movable pulley is the _________ lever.

4.Are the indications of the two dynamometers the same?

5. Compare the relationship between F1, F2, F3 and object weight G.

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For more information about the "Pulley Machinery and Work" PPT courseware, please click on the "Pulley PPT Machinery and Work PPT" tab.

Five PPT charts of the relationships between pulley block designs:

This is a PPT chart of the relationship between five pulley block designs, in .PPTX format;..

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Update Time: 2024-11-19

This template belongs to Physics courseware Beijing Normal University eighth grade physics volume 2 industry PPT template

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