"Classified Comprehensive Training" Work and Mechanical Energy PPT

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"Classified Comprehensive Training" Work and Mechanical Energy PPT

Part One: Breakthrough of Core Points

1. Gong

1. If a force acts on an object and the object moves a certain distance in the direction of the force, the force is said to have done work on the object. Doing work involves two necessary factors: one is ______________ and the other is ____________________________. There are three situations in which no work is done: __________, __________, and ___________.

2. Unit: The unit of work is _____, which has a special name called _____, or ___ for short, and its symbol is ___; 1 N·m=1 J.

3. Calculation: In physics, work is equal to the product of ____________________; formula: _______.

4． Physical meaning: Power is a physical quantity that represents the work done by an object. High power means that the work done is _____, the work done per unit time is ____.

5. Definition: The ratio of _____ to ____________ is called power, represented by the symbol ____.

6． Definition: ________.

Formula derivation: P=Wt=Fst=Fv.

7. Unit: The international unit of power is _____, abbreviated as ____, and its symbol is ____. The commonly used unit of power in engineering technology is ________. The relationship between the two units is _____________.

8. Measurement of climbing power

(1) Experimental equipment: ____________________.

(2)Physical quantity to be measured:_________________________.

(3) Design experiment: ① Use a scale to measure the mass, recorded as m; ② Use a leather tape measure to measure the height of the floor climbed, recorded as h; ③ Use a stop watch to measure the time taken to climb the floor, recorded as t.

Power expression: ____________.

3. Mechanical energy

9. Energy: If an object can ________, we say that the object has energy. The unit of energy is ________.

10． kinetic energy

(1)Definition: The energy an object has due to _____ is called kinetic energy.

(2) Determining factors: The magnitude of kinetic energy is determined by _____ and _____; the greater the mass, the greater the speed, and the kinetic energy is _____.

11． gravitational potential energy

(1) Definition: Near the earth’s surface, the energy possessed by an object due to ____________________ is called gravitational potential energy.

(2) Determining factors: The magnitude of gravitational potential energy is determined by __________ and _________; the greater the mass and the higher the position, the gravitational potential energy is _____.

12． Elastic potential energy: The energy an object has due to the occurrence of ________ is called elastic potential energy. The magnitude of elastic potential energy is related to the material of the object and the degree of elastic deformation.

13． Mechanical energy

(1)Definition: _____ and _____ are collectively referred to as mechanical energy.

(2) A large number of research results show that if only kinetic energy and potential energy are converted into each other, the total mechanical energy is _____, or in other words, mechanical energy is _____.

Comprehensive classification training PPT, the second part of the content: teaching material picture display

Proposition 1 Necessary conditions for doing work

When the athlete lifts the barbell, he/she _______ the barbell. When the athlete lifts the barbell above his head and is still, he/she _______ the barbell (please fill in the first two blanks with "doing work" or "doing no work"). It can be seen that the force will do work only when the direction of the force and the direction of the moving distance are ______.

Proposition point 2: Compare the magnitude of power

(1) An old man and a child with different weights walk up to the fifth floor. They overcome gravity and do ____ (choose "same" or "different").

(2) The adult has greater mass than the child. If the two of them reach the fifth floor in the same time, it means that the adult does ____ (optional "faster" or "slower") than the child.

(3) In physics, the speed of work done by an object is expressed by _____.

Proposition 3: Mechanical energy conversion

(1) The roll moves downward from the highest point, and the ______ energy of the roll is converted into ____ energy.

(2) The roll moves upward from the lowest point, and the ____ energy of the roll is converted into _______ energy.

(3) During the movement of the rolling pendulum, the maximum rising height always gradually decreases. The reason for this phenomenon is: ____________________________. If friction and other resistances are not taken into account, the maximum height of the rolling pendulum will decrease by _____ (optional "yes" or "no") during the movement.

Proposition 4: Conservation of mechanical energy

(1) pendulum

① When the pendulum moves from point A to point B, _______ energy is converted into ____ energy.

② When the pendulum moves from point B to point C, _____ energy is converted into _______ energy.

③A large number of experimental results show that if only kinetic energy and potential energy are converted into each other, the total mechanical energy is _____, or in other words, mechanical energy is _____.

(2) Artificial earth satellite

Artificial earth satellites orbit the earth outside the atmosphere and are not subject to air resistance. They only have the conversion of _____ and _____, so the mechanical energy _____. When the satellite is at apogee, its potential energy is the most ____. When it moves from apogee to perigee, its potential energy _____ and kinetic energy _____; when it moves from perigee to apogee, its potential energy _____ and kinetic energy _____.

Comprehensive classification training PPT, the third part: reproduction of key experiments

Experiment to explore the factors that affect the magnitude of kinetic energy

(1) Experimental device: As shown in Figure 11-T-6 (mA>mB).

(2) Experimental methods: _____ method and ________ method.

(3) Experimental analysis

① By comparing experiments A and B, it is found that the kinetic energy of the ball is related to the _____ of the ball.

② By comparing experiments A and C, we found that the kinetic energy of the ball is related to the _____ of the ball.

(4) Evaluation of the experimental plan: After completing the experiment, some students believed that in order to make the wooden block move farther on the horizontal surface, the horizontal surface should be made smoother. It would be better if the horizontal surface was absolutely smooth (no friction). Do you agree with this view? Please give reasons: ______________________________________________________________________________________.

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

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Update Time: 2024-08-18

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

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