"Power" Simple Machine Power PPT Courseware 2

Description

"Power" Simple Machine Power PPT Courseware 2

1. Create situations and introduce new lessons

Want to discuss:

Which method is faster: digging with an excavator or digging alone with a worker? What problem does the scene in the picture illustrate? Are there any similar examples?

2. The concept and calculation formula of power

Do students still remember how to express the speed of an object's movement?

What method can be used to compare how quickly an object does work?

Discussion: What method can be used to express the speed of work done by an object conveniently and accurately?

Tip: Remember the concept of speed we learned? Can you get some inspiration from it?

Power

Concept: The work done per unit time is called power.

Formula: P=W/t

unit:

SI unit: Watt, symbol W

Commonly used units: kilowatt (kW), megawatt (MW)

Example: On a construction site, the mass of a cement board is 0.7t. The crane lifts it to a height of 4m at a constant speed within 15t. What is the power of the crane to lift the heavy object?

Tips: First calculate how much work the crane does, and then find the work done per unit time. This is the power.

The pulling force of the crane is equal to the weight of the object

F=G＝mg＝0.7×1000Kg×10N/Kg=7×103 N

The distance the object moves in the direction of the pulling force S=4m

So the work done by the crane is

W=Fs=7000N×4m＝2.8×104J

The power of the crane to lift the cement slab is

P=W/t=2.8×10 J/15s=1.9×103 W

3. Knowledge application and transfer

Decide whether the following statements are correct:

1. The more work the machine does, the greater the power;

2. The less time it takes for the machine to do work, the greater the power.

3. In the same time, the more work the machine does, the greater the power;

4. The faster the mechanical work is done, the greater the power;

5. The more work the machine does, the less time it takes and the greater the power.

expansion of knowledge

Object translation exercises 12 questions in the supporting exercise book

Why do drivers often use gear shifting to reduce speed when a car goes uphill?

Tip: P=W/t, W=FS

4. Summary

1. The concept of power: The work completed per unit time is called power.

2. The physical meaning of power: It indicates how quickly an object does work.

3. Calculation formula: P=W/t Unit: Watt Kilowatt

4. The significance of various mechanical powers in life and the application of power knowledge.

Keywords: power teaching courseware, simple mechanical work teaching courseware, Lujiao version eighth grade physics PPT courseware download, second volume, eighth grade physics slide courseware download, power PPT courseware download, simple mechanical work PPT courseware download, .PPT format;

For more information about the "Simple Mechanical Work Power" PPT courseware, please click on the Simple Mechanical Work ppt Power ppt tab.

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Update Time: 2024-11-22

This template belongs to Physics courseware Lu Jiao Edition Eighth Grade Physics Volume 2 industry PPT template

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