"Pulley" Mechanical and Work PPT Courseware 4

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"Pulley" Mechanical and Work PPT Courseware 4

Pre-study tips

Do you know about pulleys? Talk about the pulleys you have seen.

______________ is called a fixed pulley.

_______________ Call the pulley.

Think about it, where are pulleys used in life?

How do you recognize pulleys? What does the pulley do?

We pull down on the rope and the flag rises. Do you know what's on the top of the flagpole?

Definition: A pulley that does not move with the object is called a fixed pulley.

Question: What are the benefits of using fixed pulleys?

Characteristics of fixed pulley

Using a fixed pulley is not labor-saving, but it can change the direction of the power (explain the change in the direction of the power).

Definition: A pulley that moves with an object is called a toggle pulley

Experimental inquiry: What are the benefits of using a moving pulley?

Features of moving pulley:

Using a movable pulley can save half the effort, but it takes twice the distance and cannot change the direction of the pulling force.

A pulley block is composed of a fixed pulley and a movable pulley."

Question: What are the advantages of using pulley blocks?

The characteristics of the pulley block: it can save labor and change the direction of the force. When using the pulley block, the pulley block uses several ropes to hang the object, and the force used to lift the object is a fraction of the weight of the object.

Class summary

What did you learn from this class? What are the gains?

Classroom testing

(1) If the weight in the picture is 20N and the center of the movable pulley is 4N, please calculate the pulling force F in the picture.

(2) Please draw the correct winding method in the pulley block in the figure below so that the pulling force is one-half and one-third of the weight of the object respectively.

(3) As shown in the figure, a worker uses force F to move an object A weighing 800N 6m in the horizontal direction at a constant speed. It is known that the friction between A and the ground is 0.25 times the gravity, excluding the weight of the pulley and friction. Here In the process, the size of this F is ____.

(4) Please design a pulley block using two fixed pulleys and one movable pulley to lift a 3000N weight. The rope weight and friction are not taken into account. Calculate the magnitude of the pulling force F.

(5) A rope can only withstand a force of 5000N. If it is used to lift a weight of 16000Nd, what kind of pulley should be selected? Draw the winding method.

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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.

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

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Update Time: 2024-11-11

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

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