"Power" work and mechanical energy PPT teaching courseware

Description

"Power" work and mechanical energy PPT teaching courseware

Part One Content: Classification Practice of Knowledge Key Points

Knowledge point 1 Power

1. Figure 11-2-1 shows the scene when the old man and the child go upstairs. If you compare the speed of work done by two people when they go upstairs, you can compare _________ when the time is the same; you can also compare _________ when they do the same work.

2. Power is a physical quantity that represents the work done by an object _____, represented by the symbol ___, and its magnitude is equal to the ratio of ____ to ____________, represented by the formula ______. The international unit of power is ______, the common unit is _______, 1 kW = ______W.

3． A diesel tractor has a power of about 9 kW and a crane has a power of about 320 kW.

(1)The physical meaning of 9 kW is _______________.

(2) During normal operation, the work done by the tractor in the same period of time is ___ than that of the crane.

4. Figure 11-2-2 shows a common scene at a construction site. From the scene shown in the picture, it can be seen that the excavator does ____ (choose "fast" or "slow") compared to people. The reason for your judgment is ____________________ , we use ______ to express how quickly an object does work.

Knowledge point 2 Calculation of power

6． A weightlifter lifts a 1700 N barbell 2 m high in 2 s. He does ______J work on the barbell, and the power of the work is ______W.

7. A worker uses a horizontal thrust of 100 N to push an object weighing 500 N at a constant speed of 0.5 m/s on a level ground, causing it to move 10 m in the horizontal direction. The work done by gravity during this process is ____J , the horizontal thrust power is _____W.

8. The power of the engine of a certain model of car with a mass of 1.2 t is 6×104 W. The car travels at a constant speed for 5 minutes, and the work done by the traction force is ________J.

9. An object moves in a straight line at a constant speed in the horizontal direction under the action of horizontal thrust. The power of the thrust is 1000 W, and the work done by the thrust is 10000 J. Then the work time is ____s.

10. On a level ground, a horizontal pulling force of 50 N is used to pull a car with a weight of 100 N forward 10 m at a constant speed. The time taken is 20 s. Find the process:

(1) The speed of the car.

(2) The work done by the pulling force.

(3) The power of pulling force.

Knowledge point 3 Measurement of power

11. After learning about power, Xiaogang wanted to roughly measure his power when doing pull-ups on the horizontal bar, as shown in Figure 11-2-3.

(1) The principle based on the experiment is (write the formula) _____.

(2) Required measurement tools: _______, ______, ________.

(3) Xiaogang measured his own mass m, the time t it took him to do pull-ups n times in succession, and measured the time ____________ he took each time he did a pull-up. Then the expression for his power when doing pull-ups is ________.

Power PPT, part 2: Comprehensive training with regular methods

12. A student's mass is about 50 kg. He walks from the first floor to the second floor of the teaching building at a normal speed. Please estimate the power of the student going upstairs during this process to be closest to ( )

A． 1 W B. 10 W

C． 100 W D. 1000W

13. Figure 11-2-4 shows the relationship between the work done by objects A and B and the time required. It can be seen from the figure that the power of object A is compared with the power of object B ( )

A． P A＞P B

B. P A＜P B

C． P A = P B

D. unconfirmed

14． As shown in Figure 11-2-5, the wooden box is pulled along the inclined plane and the horizontal plane with equal pulling force F. The direction of the pulling force and the direction of movement are always the same. The movement time tab>tcd, and the movement distance sab=scd. Compare the two situations. Work and power done by the pulling force ( )

A． Section ab does more work

B. Segment ab does the same amount of work as segment cd

C． AB segment power is larger

D. The power of segment ab is the same as that of segment cd

15. On Sunday, Xiao Ming went hiking with his father. It took Xiao Ming 20 minutes to climb to the top of the mountain, and it took his father 25 minutes to climb to the top of the mountain. The father's weight is 1.5 times that of Xiao Ming, then the ratio of the power of work done by Xiao Ming and his father when climbing is ( )

A． 5:6 B． 6:5

C． 15∶8 D. 2:3

16． The height difference of a waterfall (height difference between the top and bottom of the waterfall) is about 100 m. In 0.1 s, 18 kg of water flows through the top of the waterfall and falls to the bottom of the waterfall in 4.5 s. Then when the water falls from the top to the bottom, the power of work done by gravity is approximately ( )

A． 4×102 W B. 4×103W

C． 1.8×104 W D. 1.8×105 W

17． The speed of a car moving in a straight line at a constant speed on a straight road is 10 m/s, and the resistance the car experiences is 8×103 N. The power of the car is ________W.

18. Two containers A and B have the same mass. The crane lifts container A by 10 m at a constant speed of 0.1 m/s for the first time, and lifts container B by the same height at a constant speed of 0.2 m/s for the second time. If air resistance is not taken into account, when comparing the pulling force of the steel rope on the container twice, the first time _____ the second time; comparing the power of the steel rope acting on the container twice, the first time _____ the second time. (Please choose "greater than", "less than" or "equal to")

Power PPT, the third part: practical practice of high-frequency test questions

21．2018·Lianyungang As shown in Figure 11-2-7, a block slides down from stationary point A on a smooth slope, and B is the midpoint of the slope AC. Assume that the work done by gravity on the block AB is W1, and the gravity The power is P1; in the BC section, the work done by gravity is W2, and the power of gravity is P2, then the following relationship is correct ( )

A． W1>W2, P1>P2 B. W1=W2, P1=P2

C． W1＝W2, P1＜P2 D. W1＜W2，P1＜P2

Keywords: Free download of PPT courseware for the second volume of eighth-grade physics published by the People's Education Press, power PPT download, work and mechanical energy PPT download, .PPT format;

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

"Work and Power" Law of Conservation of Mechanical Energy PPT quality courseware:

"Work and Power" Law of Conservation of Mechanical Energy PPT high-quality courseware Part 1: Core literacy goals Physical concepts Understand work and power, clarify the meaning of positive work and negative work, and be able to correctly distinguish average power and instantaneous power. Scientific thinking and ability to apply the formula W=Flcos..

"Work and Power" Law of Conservation of Mechanical Energy PPT excellent courseware:

"Work and Power" Excellent Courseware on the Law of Conservation of Mechanical Energy PPT Part One Content: Learning Objectives 1. Master the formula of work W=Flcos and the applicable scope of the formula, and be able to use the formula of work to calculate. 2. Understand the concepts of positive and negative work, and be able to Calculate multiple forces based on the formula...

"Problems with Multiple Gears of Electrical Appliances" Electric Power PPT:

"Multi-gear Problems of Electrical Appliances" Electric Power PPT Overview of the topic The multi-gear problem of electrical appliances is a comprehensive problem that integrates electric heat, electric power and electric power. It is the focus and difficulty of electrical problems. Its main types include multi-speed problems with electrical appliances and multi-speed problems with electric heaters..

File Info

Update Time: 2024-11-20

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

Preview