"Pulley" Mechanical and Work PPT Courseware

Description

"Pulley" Mechanical and Work PPT Courseware

think

Using a fixed pulley can change the direction of the force, but it cannot save effort; using a movable pulley can save effort, but it cannot change the direction of the force.

Then can we combine the two to form a pulley block, so that it can change the direction of force and save effort?

1. Pulley block

Exploration experiment: Explore the characteristics of pulley blocks

① Combine a fixed pulley and a movable pulley to form a pulley block. Discuss. How many combinations can you design? Draw your plan.

Analyze experimental results

Comparing experiments 1 and 2, the pulling force of the spring dynamometer when using the pulley block is 1/2 of the weight of the object.

Comparing experiments 1 and 3, the pulling force of the spring dynamometer when using the pulley block is 1/3 of the weight of the object.

summary

The magnitude of the pulling force F is related to the number n of rope segments used to lift the movable pulley. The moving pulley is hoisted by several lengths of rope, and the force used is a fraction of the weight of the object, that is:

F =1/n G

The distance s moved by the tension F (the free end of the rope) is n times the rising height h of the object, that is:

s = nh

example

1. In the pulley block shown on the right:

(a) If the weight of the movable pulley G is not included, what is the pulling force F?

F =1/5 G object

(b) If the weight of the movable pulley G cannot be ignored, what should the pulling force F in the figure be equal to?

F =1/5 (G object + G wheel)

2. As shown in the figure, the weight of object A is 100 N, and the pulling force on the hook holding the heavy object is _____ N. The force exerted by a person pulling the rope at a constant speed is _____ N (the dead weight of the movable pulley is not included).

3. Among the four pulley blocks as shown in the figure, the one in Figure ______ can save half the effort, the one in Figure ______ is the most laborious, and the one in Figure ______ and Figure ______ require the same amount of force.

4. Use the pulley set as shown in the figure to pull object A. How to wind the wire with the least effort? Draw a winding diagram.

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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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Update Time: 2024-10-26

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

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