"Measurement of Energy Transformation" PPT courseware

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"Measurement of Energy Transformation" PPT courseware

Part One: Learning Objectives

1. Know the physical quantity that describes how fast an object does work—power.

2. Know the power of common objects in life.

3. Be able to use the power formula to solve for power.

Measurement of energy conversion PPT, part 2: review questions

A classmate participated in the general cleaning and was responsible for carrying water. Try to analyze whether he did any work on the bucket in the following process.

(1) Carry water and walk up the stairs to the second floor;

(2) Carry water and walk along the corridor to the classroom door;

(3) Hold water and stand at the door for a while.

(1) Doing work

(2) No work done

(3) No work done

Measurement of Energy Transformation PPT, Part 3: My Thoughts

As shown in the figure, a person lifts a bucket weighing 100N and goes up the stairs from the first floor to the third floor at a speed of 2m/s. How much work does the person do on the bucket? If the person goes from the first floor to the third floor at a speed of 5 m/s, how much work does the person do on the barrel?

Solution: W=Fs=Gh=100N×6m=600J

Answer: The person did 600J of work on the barrel.

Is there any difference between doing the work twice? What does this series of events illustrate?

Measurement of energy conversion PPT, Part 4: Calculation of power

Example 1. A crane lifts a weight of 60,000 N up to a height of 25 meters at a constant speed in 5 minutes. How many kilowatts does it have?

Solution: W=Fs=60000N×25m=1500000J

P=W/t=1500000 joules/300 seconds=5000 watts=5 kilowatts

Answer: The power of the crane is 5 kilowatts.

Example 2. An object with a mass of 50 kg uses a horizontal thrust of 50 N to move it at a constant speed of 10 meters on a rough horizontal surface at a speed of 2 m/s. Question (1) How powerful is it? (2) How powerful is gravity?

Solution: (1)t=s/v=10 meters/2 meters/second=5 seconds

W=F×s=50N×10m=500J

P=W/t=500 joules/5 seconds=100 watts

(2) Because there is no passing distance in the direction of gravity, W=0, P=0.

Measurement of energy conversion PPT, Part 5: Class summary

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

2. Calculation formula: power = work/time P = W/t

3.Unit: Watt (W)

1 watt = 1 joule/second, 1 kilowatt = 1000 watts, 1 megawatt = 106 watts.

Measurement of energy conversion PPT, Part 6: Comparison

True or false

1. The greater the power of the machine, the more work it can do.

2. The smaller the power of the machine, the slower the work will be done.

3. The smaller the power of the machine, the lower the efficiency.

4. The greater the power of the water pump, the more water will be pumped.

Compare who has more power

Xiao Ming and Xiao Hong want to compare who can go upstairs more efficiently. What scientific quantities need to be measured? What measuring instruments are needed? How should it be measured?

Keywords: Zhejiang Education Edition ninth grade science PPT courseware free download, measurement of energy conversion PPT download, .PPT format;

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"Measurement of Energy Transformation" PPT:

"Measurement of Energy Transformation" PPT Part One: Learning Objectives 1. Understand the concept of work and know the two necessary factors of work. Understand the relationship between the transformation of energy and work. 2. Know the calculation formula of work, know the unit of work, and initially master the calculation method of work. ..

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Update Time: 2024-07-03

This template belongs to science courseware Zhejiang Education Edition Ninth Grade Science Volume 1 industry PPT template

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