"Force" Force PPT (the three elements of force and the interaction of forces in Lesson 2)

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"Force" Force PPT (the three elements of force and the interaction of forces in Lesson 2)

Part One Content: Basic Knowledge Key Points

Knowledge point 1: The three elements of force and the schematic diagram of force

1. As shown in the figure, when using a wrench to tighten a nut, generally the nut can be tightened in the clockwise direction and loosened in the counterclockwise direction. This shows that the effect of force is related to the direction of the force; if The same force is used to twist points A and B, and it is easier to twist at point A. This shows that the effect of force is related to the point of action of the force.

2. In the process of pushing the door, Xiao Ming can experience the influence of the three elements of force on the effect of force, as shown in the figure. At point A on the door, push the door with forces of the same direction and different sizes. The greater the force, the easier it is to push the door open. This shows that the effect of the force is related to the size of the force. At point B on the door, use different forces of different sizes. Pushing the door with equal force but different directions can push the door open or close, which shows that the effect of force is related to the direction of the force; at points A and B on the door, push the door with forces of the same direction and equal magnitude. It is easier to push the door open at point B than at point A, which shows that the effect of force is related to the point of action of the force.

3. As shown in the picture, Xiaohua pulls the car with a rope to walk. Please draw a schematic diagram of the pulling force F of the rope on the car.

Knowledge point 2: The effects of forces are mutual

4. When playing volleyball, if you hit the volleyball hard, your hands will hurt. This shows that the forces between objects are mutual.

5. As shown in the figure, when the electric fan is working, the air will flow from stillness, and at the same time, the car will move to the right (optional "left" or "right"). The reason is that the forces between objects are mutual.

6. In boxing matches, sometimes boxers are knocked down. Regarding this phenomenon, the following analysis is correct (C)

A. The attacker receives a large amount of force

B. The person who was hit suffered great force

C. The force on both is the same

D.Unable to judge

Power PPT, part 2: improvement of comprehensive capabilities

7. In a volleyball match, when the ball is passed by the setter, the main attacker smashes the ball with a constant force. The landing point and rotation of the ball are different, which shows the effects of different directions and action points of the force. Also different.

8. The football played on the field sometimes rolls against the ground and sometimes flies into the air. This is mainly caused by the different "action points" of the force when athletes kick the ball.

9. When a dog sled moves forward, the dogs exert a pulling force on the sled, and at the same time, the sled also exerts a pulling force on the dogs. The three completely different elements of these two forces are the direction and the point of action.

10. When swimming, Xiao Tao strokes backward to obtain forward force, which shows that the effects of forces are mutual; when he reaches the end point, he stops moving due to the force from the pool wall, which shows that the force changes his state of motion. .

11. Make the top of a large plastic beverage bottle into a bullet shape, fill the bottle with about 1/3 of water, and seal the mouth of the bottle with a rubber stopper with a valve core to make a "water rocket". In order to make the water rocket fly stably, side wings can also be installed, as shown in the picture. Use a pump to pump air into the bottle through the valve core. When the air pressure increases to a certain level, the high-pressure gas will spray the water downward, and the rocket will rise upward. The force-exerting object for a water rocket to take off is water; the working principle of a water rocket is that the forces between objects are mutual.

12. When two eggs collide, one will always break first. Which of the following statements is correct (C)

A. Only the unbroken eggs are stressed

B. Only the broken egg bears the force

C. Both eggs are stressed

D. It is unknown which egg is affected by the force

13. Which of the following statements about force is incorrect (D)

A. When skating, if a person pushes the wall hard, the person will move back because the person is also pushed by the wall.

B. When standing in the long jump, your feet should push back hard, indicating that the forces between objects are mutual.

C. The diver steps on the springboard and his body bounces upward, indicating that the effects of force are mutual.

D. Only the size of the force will affect the effect of the force

Power PPT, the third part: Expand, explore and break through

21. As shown in the picture, fix the lower end of a thin steel ruler. Now push it with different forces to cause it to deform as shown in Figures A, B, C and D. If F1=F3=F4>F2, then:

(1) Figures A and B can illustrate that the effect of force is related to the magnitude of the force;

(2) Figures A and C can illustrate that the effect of force is related to the direction of the force;

(3) Figures A and D can illustrate that the effect of force is related to the point of action of the force;

(4) The experimental method used in this experiment is the controlled variable method.

Keywords: Free download of PPT courseware for the second volume of eighth-grade physics from the People's Education Press, download of force PPT, download of the three elements of force and the interaction of forces PPT, .PPT format;

For more information about the PPT courseware "Three Elements of Force and the Interaction of Forces", please click the "Three Elements of Force and the Interaction of Forces" ppt tag.

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Update Time: 2024-11-05

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

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