What is the focus of junior high school physics, what content should be mastered, and how to learn i

Middle School Physics Focus:

Understand the characteristics of light, electricity, sound, force and heat, know the basic probability, use formulas flexibly, learn to explain some phenomena in life, and be able to operate some experiments.

Learn from the following aspects:

1. Preview before class and ask questions; 2. Listen attentively in class and actively participate in the discussion of problems; 3. Observe more experimental phenomena; 4. Draw conclusions from experimental phenomena; 2. Review and consolidate after class, and ask why? For example, the production of sound, how is sound produced and what does it take to propagate?

Secondly, the application of the propagation formula? Calculation of echo?

Finally, physics doesn't need to be rote memorization, more understanding, more observation, I'm in junior high school physics now, you can ask me questions.

The difficulties of junior high school physics knowledge include mechanics, circuit conversion, lever principle, motion, application of Archimedes' principle, and conservation of energy.

For many junior high school students, physics learning is a very headache, many problems have been learned, but it is still easy to make mistakes when doing problems, do and make mistakes, make mistakes and do mistakes, and repeat repeatedly to the end still do not understand, in fact, the difficulties of junior high school physics knowledge are only so many parts.

1. Circuit conversion problems.

When we learn physics and electricity in junior high school, we find that this part is often very abstract, and a lot of electrical knowledge depends not only on memorization but also on understanding, which is the reason why most students think that electricity is a difficult point in junior high school physics. In fact, regarding circuit conversion, we only need to start from the positive electrode, carefully observe the number of shunts at each node according to the flow direction of the current, and then draw back in turn until the negative electrode can complete the conversion. Usually through some converted circuit diagrams, we can clearly see the relationship between series and parallel connection of various electrical appliances, so it is very important to draw a circuit diagram.

2. Archimedes' principle

The application of Archimedes' principle is mainly divided into two situations, one is when the object is floating, and the other is when the object is immersed. When the object is floating, we can find the magnitude of the buoyancy according to the formula g f floating, and then find the volume of the object immersed according to the Archimedes principle. If the object is in a submerged state, the buoyancy force should be calculated according to the formula v object v row, and then other physical quantities can be analyzed according to the buoyancy force.

3. Mechanical energy and energy part

For the mechanical energy and energy part, there are usually three ways to do the problem, the first is to determine the state to find the function, the second is to clarify the benign mechanical energy, and then look at the process force to do the work, at this time the work outside the gravity is 0, the third is to determine the state to find the amount of energy, and then look at the work done in the process, as long as there is work, there is a change in energy. As long as these three methods are mastered, the problem of mechanical energy is generally not too difficult.

The main difficulty lies in the fact that children do not have a clear understanding of physics, do not know the laws and laws of physics, and have not cultivated a certain logical thinking ability.

There are many difficulties because there are many physical formulas, so you must memorize the formulas clearly, and you must memorize more concepts and knowledge points during the learning process.

I think the difficulty in junior high school physics is that people don't understand circuits very well, because circuits are very complex.

The difficulty of junior high school physics knowledge lies in understanding a knowledge point and how to use this knowledge point to solve problems.

1. Quality m

2. Temperature t

3. Speed v

4. Density

5. Force (gravity) f

6. Pressure p

7. Power w8, power p

1. Force (f): Force is the action of an object on an object, and the action of force between objects is always reciprocal. Unit of force: Newton (n).

2. The three elements of force: The magnitude, direction, and point of action of force are called the three elements of force. The diagram of the force should be scaled; Schematic diagram of the force, not scaled.

3. Gravity g: The force experienced by an object due to the attraction of the earth. Directions:

Straight down. Gravity and mass relationship: g=mg m=g g, g=kN. kg.

Reading: Niu Xiang This kilogram of silver means that the gravity of an object with a mass of 1 kilogram on the earth is a cow.

1. The magnitude and direction of the force: The force is a physical quantity, and gliding has the magnitude and direction, which can be represented by arrows.

2. The role of force: Force can change the state of motion of an object, such as speed, direction and position.

3. Types of force: The types of chain rulers of force include gravity, elasticity, friction, electromagnetic force, etc.

4. Balance of forces: When two sheds let high or multiple forces balance, the motion state of the object will not change.

5. Newton's Law: Newton's law states that the external force experienced is equal to the mass of the object multiplied by its acceleration.

The summary of key knowledge is similar to a mind map, which sorts out the content that is considered more important, and it is more convenient and convenient to understand and remember it by looking at the map for review.

1. Pressure formula: f=p (pressure) * s (force area).

2. Pressure formula: p=f(pressure) s(force area).

3. Mass formula: m = density * v (volume).

4. Work: w fs gh (lift the object high).

5. Power: p w t fv

6. The principle of work: w hand w machine.

7. Actual machinery: w total w has w extra.

8. Mechanical efficiency: w has w total.

For the definition of pressure, four main points should be emphasized:

1. When the force area is constant, the pressure increases with the increase of pressure. (The pressure is proportional to the pressure).

2. The same pressure acts on the surface of the support, if the force area is different, the pressure generated is also different. The stress area is small, and the pressure is strong; When the force area is large, the pressure is small.

3. Pressure and pressure are two completely different concepts: pressure is the force on the support surface and perpendicular to the support surface, and has nothing to do with the area of the support surface and the size of the force area.

4. There is a difference between the unit of pressure and pressure. The unit of pressure is the newton, which is the same as the unit of force in general. The unit of pressure is a composite unit, which consists of the unit of force and the unit of area.

In the International System of Units is the Newton square meter, called "Pascal", or "Pa" for short.

Physics textbook knowledge in junior high school.

Physics is the discipline that studies the most general laws of the motion of matter and the basic structure of matter, and is the research foundation of other natural science disciplines. This article shares with you tips for learning junior high school physics well.

1.Preview before class and read the textbook thoroughly

No matter what subject you are studying, the most important thing is to prepare for class and thoroughly understand the textbook. Preview allows us to understand the content of the textbook, and it can also allow us to select questions that we don't understand and listen to the lecture with them.

2.Serious and active participation in class

Listen carefully in class, especially if you don't understand what you don't understand before class, you must actively listen to the lecture, interact with the teacher in the class, and actively ask questions from the teacher.

3.Review after class and learn from the past

It is necessary to review after class, especially the knowledge points that you don't understand during the preview. Revision is the best way to deepen your impression, and if you still don't understand it when revising, you should communicate with the teacher in time.

4.Do more and practice, practice makes perfect

If you want to learn physics well, you must do a lot of exercises, apply the concepts and formulas learned in books to actual problems, and if you can do the problems handy, you can show that you have mastered the knowledge points.

5.Sort out the mistakes and deepen the memory

If you want to learn physics well, you need to prepare a problem book, write down your mistakes one by one, and then review them often to deepen your impression, so as to avoid making the same mistakes.

6.Rote memorization, theorem formulas

If you want to learn physics well, rote memorization is a must, for some fixed formulas, if the formula can't be memorized, there is no way to solve the problem, especially similar physical quantities, must be clearly distinguished.

1. Factors affecting the size of buoyancy:The density of the liquid and the volume of the object submerged in the liquid (i.e., the volume of the object expelling the liquid) are not directly related to the volume of the object. If the object is completely submerged in the liquid, the magnitude of the buoyancy force is independent of the depth of the object.

2. Household circuits and safe electricity:All electrical appliances in the home circuit are connected in parallel, and the switch is connected between the electrical appliances and the live wire. The connection of the socket is:

Left zero right fire on grounding. For electrical appliances with a metal casing, the metal casing must be grounded.

3. Balance: Equal-large, inverse, collinear. There is only one stressed object. (The object is at rest under the action of gravity and supporting forces).

4. Interaction force:: Equal-large, inverse, collinear. The stressed objects are two. (The pressure of the cup on the table and the support force of the table top on the cup).

5. Effect of force:It is possible to change the shape of the object (elongating the rubber band) and the state of motion of the object (playing a table tennis ball with a racket).

The knowledge points of physics pulley in junior high school are as follows:

1. The pulley is a small wheel with a groove around the perimeter that can rotate around the shaft. A pulley is a simple machine that can rotate around a central axis consisting of a grooved disc that rotates around the central axis and a flexible rope (rope, tape, steel cable, chain, etc.) that crosses the disc.

2. Fixed pulley: When the plastic pulley bearing uses the pulley, the pulley with the fixed position of the shaft is called the fixed pulley.

3. The fixed pulley is essentially an equal arm lever, which is not labor-saving, but can change the direction of force. The power arm and resistance arm of the lever are respectively the radius of the pulley, and since the radius is equal, the power arm is equal to the resistance arm, and the lever is neither labor-saving nor labor-intensive.

4. When in use, the position of the pulley is fixed; The fixed pulley is essentially an equal-arm lever, which is effortless and effortless, but can change the direction of the force. The power arm and resistance arm of the lever are respectively the radius of the pulley, and since the radius is equal, the power arm is equal to the resistance arm, and the lever is neither labor-saving nor labor-intensive.

5. According to whether the position of the central axis of the pulley moves, the pulley can be divided into "fixed pulley" and "movable pulley"; The central axis of the fixed pulley is fixed, and the central axis of the movable pulley can be moved, each with its own advantages and disadvantages. And the fixed pulley and the movable pulley are assembled together to form a pulley block, which not only saves force but also can change the direction of force.