"Textbook Knowledge Combination" Power PPT

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"Textbook Knowledge Combination" Power PPT

Part One: Breakthrough of Core Points

1. Force

1. Definition: Force is the function of ____________. Force cannot exist without objects.

Explanation: The action of force is always ______. The two objects that act are one that exerts force and the other that receives force. The object that exerts force and the object that receives force always appear at the same time.

2. Unit: In physics, force is represented by the symbol _____, the unit is ______, or cattle, the symbol is _____.

3． The effect of force: first, it can ____________________, and second, it can _____________.

4. Three elements of force: _______, _______, and ________ of force are called the three elements of force.

5. Schematic diagram of force: Use a ____________ to represent the force, the starting point or end point of the line segment represents the ________ of the force, the arrow represents the _______ of the force, and the length of the line segment represents the ______ of the force.

2. Elasticity Spring dynamometer

6. Two characteristics: When an object deforms, it exhibits two characteristics, namely ______ and ______.

7. Elastic force: The force generated by an object due to _________ is called elastic force. For the same object, the size of the elastic force is related to _____________.

8. spring dynamometer

(1) Principle: Within the elastic limit, the more _____ the tension on the spring, the more _____ the elongation of the spring.

(2) Usage: ① Before use, gently pull the hook of the spring dynamometer back and forth to see if the pointer can be reset; ② Recognize the range and graduation value of the spring dynamometer, and set the pointer to zero; ③ Must be used when measuring Keep the axis direction of the spring and the direction of the measured force ______ to avoid friction; ④ When reading, the line of sight should be ______ with the dial.

3. Gravity

9. Reason: Objects in the universe, from as large as celestial bodies to as small as dust, all have a force of attraction to each other. This is universal gravitation. Gravity is caused by the Earth's ______ on objects around it.

10. Definition: The force exerted on an object due to ___________ is called gravity, represented by the letter _____.

11． Object exerting force of gravity: ______; Direction of gravity: _______.

12. The gravitational force on an object is ______ with its mass, written as the formula: ________. g=________, physical meaning: _______________________________.

13. center of gravity

(1)The equivalent point of action of gravity is called _____.

(2) The position of the center of gravity of an object is related to the shape and mass distribution of the object. An object with a regular shape and evenly distributed mass has its center of gravity at its _________.

(3) The center of gravity of an object can be on the object or outside the object. For example, the center of gravity of a flat plate is on the board, but the center of gravity of an iron ring is not on the ring.

(4) The position of the center of gravity has nothing to do with the location, placement state and motion state of the object.

Teaching material knowledge sorting PPT, the second part of the content: teaching material picture display

Proposition 1: Explore the effects of force

(1) As shown in Figure 7-T-1 A and B, squeeze the plasticine hard, press or pull the spring, and observe the shape of the plasticine and spring _______ (optional "change" or "unchanged"), Explain that force can change the _______ of an object.

(2) As shown in Figure C, let the small iron ball roll down the incline, place a magnet along its direction of movement, with the magnetic pole facing the small iron ball, and observe that the small iron ball moves at a speed of ______ (optional "Add" "large", "decrease" or "unchanged"); as shown in Figure D, let the small iron ball roll down the slope, place a magnet on the side of its movement path, the magnetic pole is perpendicular to the movement path, observe the small iron ball The direction of movement of the ball ______ (optional "change" or "unchanged"). The above phenomenon shows that force can change the __________ of an object.

Proposition Point 2: Explore the role of forces between objects

As shown in Figure 7-T-2, a student wearing roller skates is pushing hard against the wall. What will happen is ______________.

The student pushed the wall with a force exerting an object of ______ and a force-receiving object being ______. At the same time, the wall had a reaction force on the student. The force exerting object was ______ and the force-receiving object was ________. It can be seen that the effect of force between objects is ______; the object exerting force is also the object receiving force, and the object receiving force is also the object exerting force. To produce the effect of force, there must be at least ______ objects.

Proposition 3: The direction of gravity

As shown in Figure 7-T-3, construction workers often use thin wires to hang a heavy object and let the heavy object hang freely to form a plumb line.

Use this to check whether the wall being built is _______.

This is because the heavy object is acted upon by ______ force.

The direction of this force is _________.

Teaching material knowledge sorting PPT, the third part: reproduction of key experiments

Experiment: Explore the relationship between gravity and mass of an object

(1) Experimental equipment: several hook codes (50 g), ____________.

(2)Experimental steps

① Use a spring dynamometer to measure the gravity exerted by a hook code and fill it in the form.

② Use a spring dynamometer to measure the gravity on the two hook codes and fill it in the form.

③ Use a spring dynamometer to measure the gravity on the four hook codes and fill it in the form.

(3)Experimental data record sheet

(4) Experimental conclusion: ____________________.

(5)Communication and evaluation

①According to the relationship between gravity and mass, it can be seen that the gravity experienced by objects with large mass is _____.

②The amount of matter contained in the same object does not change from the earth to the moon, so its ______ remains unchanged; but because the attraction it experiences on the moon is smaller than that on the earth, the "gravity" it experiences changes. ____.

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Update Time: 2024-10-18

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

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