"Pulley" Simple Machinery PPT

Description

"Pulley" Simple Machinery PPT

Part One: Preview Perception

1. Fixed pulley

2. Moving pulley

3. Pulley block

1. Concept: A device that combines a fixed pulley and a movable pulley.

2. Features: It can save effort and change the direction of force.

3. When using a pulley block to lift a heavy object, there are several sections of rope on the movable pulley to bear the weight of the object, and the force used to lift the object is a fraction of the weight of the object.

Pulley PPT, Part 2: Interactive Classroom Exercises

Features of pulley block

The amount of effort saved by the pulley block depends on the number of segments of the rope hanging the movable pulley, while the rope across the fixed pulley, including the last pull rope drawn from the fixed pulley, only serves to change the direction of the force. If friction and the weight of the rope are not considered, the rope bears the total weight of the object and the movable pulley. The pulley group uses several sections of rope to bear the object. The pulling force used to lift the object is a fraction of the total weight. The formula is expressed as F=_________; If the gravity of the movable pulley is no longer considered, the formula becomes F=__________.

The relationship between the distance s moved by the free end of the rope and the height h of the object rising is s=nh (where n is the number of rope segments hanging the movable pulley), so although using the pulley block saves effort, it costs distance.

[Example Question] (2017 Heilongjiang Suihua High School Entrance Examination) As shown in the figure, a worker uses a pulley block to lift a 200 N weight upwards to a 2 m high platform at a constant speed. The pulling force he uses is _________N, and the free end of the rope moves downwards. The distance is _________m. (Excluding rope weight, moving pulley weight and friction)

Pulley PPT, Part 3: Try the application

1. Fixed pulley and movable pulley

1. There is a pulley on the top of the flagpole for raising the flag. When the flag is raised, pull the rope downward and the flag will rise. The correct statement about this pulley is ()

A. This is a movable pulley, which can save labor

B. This is a fixed pulley, which can save labor

C. This is a moving pulley that can change the direction of force

D. This is a fixed pulley that can change the direction of force

2. Among the three pulleys shown in the figure, the movable pulley is _______. If the self-weight and friction of the pulley are ignored, when the same object is lifted at a constant speed in the directions of force F1, F2 and F3, the relationship between the magnitudes of F1, F2 and F3 is ______________.

2. Pulley block

3. Use the device as shown in the figure to lift the same object. When the weight of the pulley and friction are not taken into account, the most labor-saving method is ()

4. Student Xiaohu uses a pulley set to lift an object with a gravity of 600 N at a constant speed. If the friction force, the gravity of the movable pulley and the gravity of the rope are not taken into account, the pulling force of Xiaohu on the rope should be ()

A.600 N　B.400 N

C.300 N D.200 N

5. As shown in the picture, someone lifts an object at point A. Please draw the most labor-saving way to wind the rope in the picture.

Keywords: Free download of PPT courseware for the second volume of eighth-grade physics published by the People's Education Press, download of pulley PPT, download of simple machine PPT, .PPT format;

For more information about the "Simple Machine Pulley" PPT courseware, please click on the Simple Machine PPT Pulley ppt tab.

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Update Time: 2024-11-21

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

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