"Chapter End Summary and Improvement" Power PPT

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"Chapter End Summary and Improvement" Power PPT

Part One: Key Breakthroughs

Interaction

If one object exerts a force on another object, the object receiving the force will in turn exert a force on the object exerting the force. These two forces are equal in magnitude, opposite in direction, act on two different objects, and act on the same straight line. They can be simply summarized as foreign bodies, equivalent, opposite, and collinear. A pair of interacting forces must appear and disappear at the same time.

Typical example: As shown in the picture, the student sitting in the boat on the right pushed the boat on the left hard, and the two boats moved in opposite directions. The correct one of the following statements is ()

A. The thrust keeps the two ships moving in opposite directions.

B. The three elements of thrust exerted by the two ships are exactly the same.

C. This phenomenon shows that the effects of forces are mutual.

D. The thrust of both ships acts on people

[Analysis] The thrust makes the two ships move in opposite directions, but it is not the reason for maintaining the motion. Item A is wrong; the directions of the thrust on the two ships are different, so the three elements of the two forces are different. Item B is wrong; both The boats move in opposite directions at the same time, indicating that the forces between the objects are mutual, so item C is correct; the thrust on the two boats is not on the same object, so item D is wrong.

【Answer】C

End-of-Chapter Summary and Improvement PPT, Part 2: Experimental Activities

Experiment 1: Explore the relationship between spring elongation and tension

1. Experimental device: as shown in the figure.

2. Experimental steps

(1) Place the iron stand on the experimental table, and then hang the spring on the iron stand. When the spring is standing vertically, measure the original length L0 of the spring and fill it in the experimental form.

(2) Hang one hook code, two hook codes, three hook codes under the spring in sequence... When the hook codes are in a stationary state, measure the total length or elongation of the spring in sequence, and fill in the experimental form.

(3) According to the measured data, take the force F as the ordinate and the spring extension ΔL as the abscissa, and draw points on the graph paper according to the measured data in the table;

(4) Make the F-ΔL image of the spring. According to the distribution and direction of each point in the coordinate diagram, try to make a smooth curve (including a straight line).

3.Experimental conclusion

Within the elastic limit, the elongation of the spring is proportional to the tension on the spring.

Experiment 2: Explore the relationship between gravity and mass

1. Experimental device: as shown in the figure.

2. Experimental process

Use a spring dynamometer to measure the gravity of the hook code, and then record the mass and gravity values.

3.Experimental conclusion

The magnitude of the gravity exerted by an object is directly proportional to its mass, and its ratio is a constant value, which is approximately equal to 9.8 N/kg.

Typical example 2: When exploring the relationship between the gravity exerted by an object and its mass, measure the mass of some objects and the gravity they exert, and record the data obtained in the table.

(1) The main measuring equipment used in the experiment is __________ and __________;

(2)The purpose of conducting multiple measurements in the experiment is______;

(3) From the analysis of the data in the table, it can be seen that the greater the mass of the object, the greater the gravity it experiences (please fill in "large" or "small"), and the magnitude of the gravity experienced by the object is proportional to the mass;

(4) Let m represent the mass of the object, use G to represent the gravity on the object, and use g to represent the ratio of gravity to mass, then G=__________. The experiment measured g=__________N/kg.

Keywords: Free download of PPT courseware for the second volume of eighth-grade physics published by the People's Education Press, download of chapter-end summary and improvement PPT, download of force PPT, .PPT format;

For more information about the PPT courseware "Strength Chapter End Summary and Improvement", please click the Strength ppt Chapter End Summary and Improvement ppt tab.

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Update Time: 2024-09-22

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

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