"Gong" PPT teaching courseware on work and mechanical energy

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"Gong" PPT teaching courseware on work and mechanical energy

The first part of the content: Practice on classification of knowledge points

Knowledge point 1 Gong

1. Regarding the concept of work, which of the following statements is correct ( )

A. Whenever a force acts on an object, the force does work on the object

B. As long as an object moves a distance, a force can do work on it

C. As long as a force acts on an object and the object moves a distance in the direction of the force, the force has done work on the object.

D. When a force acts on an object and the object moves a distance, the force must have done work on the object.

2. In the four scenarios shown in Figure 11-1-1, the work done by people on the object is ()

3． In the following four pictures, what works against the gravity of the object is ( )

A. Picture A: People push a trolley across a certain distance on a level road

B. Picture B: People move the stone hard, but the stone is not moved.

C. Figure C: Forklift lifts goods from the ground to a certain height

D. Tuding: A person carrying a skateboard passes a certain distance while standing on a horizontal conveyor belt

Knowledge point 2 Calculation of work

4． Work is equal to ____ times the amount of time the object passes through _____ in the direction of the force. Calculation formula: _______, the international unit of work is _____, abbreviated as ____, represented by the symbol ____.

5. A wooden block moves forward 5 m along a straight road under the action of a horizontal pulling force of 10 N. The work done by the pulling force is ____ J. If the block weighs 30 N, the work done by gravity on the block during this process is ___ J.

6． In order to improve students' ability to safely self-rescue and use fire extinguishers, the school conducts fire safety drills. During the exercise, Xiao Ming used a vertical upward force of 60 N to lift the fire extinguisher 0.5 m from the ground. Then the work done by Xiao Ming on the fire extinguisher is ____J.

7． A football player kicks a football weighing 5 N with a force of 100 N. The ball rolls forward 30 m on the horizontal grass after leaving the foot. As the ball rolls, the work done by the athletes on the football is ( )

A. 3000JB. 500 J

C. 150JD. 0 J

8. In a certain training session (as shown in Figure 11-1-3), a weightlifter takes 3 seconds to lift a barbell with a mass of 150 kg 1.8 m. Question: (g takes 10 N/kg)

(1) How much pressure is exerted on the athlete when the barbell is stationary in the air?

(2) During the process of lifting the barbell this time, how many joules of work did the athlete do on the barbell?

Gong PPT, the second part of the content: Comprehensive training with regular methods

9．2017·A classmate in Changchun is training to throw a medicine ball. In the following scenario, the work he does on the ball is ( )

A. Holding the ball still

B. Hold the ball in your hand and move horizontally and in a straight line at a constant speed

C. lift the ball

D. The ball continues to move in the air after being thrown

10． As shown in Figure 11-1-4, the ground in Figure A is rough and the ground in Figure B is smooth. Two objects with masses m and 2m respectively move forward in the same direction under the action of a constant force of magnitude F. distance, then the following conclusion is correct ( )

A. The work done by F in Figure A is less than the work done by F in Figure B

B. The work done by F in Figure A is equal to the work done by F in Figure B

C. The work done by F in Figure A is greater than the work done by F in Figure B

D. Insufficient conditions make it impossible to determine who has done more work by F in Figure A or Figure B.

11. Student Xiao Li successively used the same force F to move the same wooden box the same distance in the direction of the force on the three surfaces A, B, and C as shown in Figure 11-1-5. The force F in these three processes The work done in is W A, W B, W C respectively. Regarding the magnitude of the work done, the following statement is correct ( )

A. W A＜W B＜W C

B. W A＞W B＞W C

C. W A = W B = W C

D. W A＝W B＜W C

12. Rope skipping is a new item in the junior high school physical education exam. Every time Xiaoqiang jumps, the work done by overcoming gravity is closest to ( )

A. 3JB. 30 J

C. 300 JD. 600 J

Gong PPT, the third part: practical practice of high-frequency examination questions

18．2018·Changsha Which of the following statements about gong is correct ( )

A. When Xiao Ming pushed the broken car hard without pushing, the pushing force did work on the car.

B. When a crane lifts a heavy object and moves at a constant speed in the horizontal direction, the pulling force of the crane does work on the heavy object.

C. When a football rolls a certain distance on a horizontal surface, gravity does work on the football.

D. When a weightlifter lifts the barbell from the ground, the weightlifter does work on the barbell

19．2018·Shaoxing Two identical objects A and B both weigh 20 N.

(1) Under the action of a horizontal thrust of 10 N, the two objects move in a uniform straight line at a speed of 2 m/s at the same time. As shown in Figure 11-1-9A, when the distance the object passes is 3 m, the thrust force The work is _____J.

(2) If objects A and B make uniform linear motion on another horizontal plane at a speed of 3 m/s under the action of a thrust of 15 N, as shown in Figure B, then the thrust of A on B at this time is _____N.

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

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

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Update Time: 2024-09-06

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

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