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1、高中物理解题思路全解全析（High school physics, problem solving, thinking, total solution, analysis）High school physics, problem solving, thinking, total solution, analysisI. ideas and methods of solving statics problems1. determine the object of study: isolate the object - -. When necessary, the subjects should
2、be converted. In this type of transformation, one case is changed to another object, one is to include the original object, but to enlarge the range and include another object.2., analyze the external forces of object, and analyze primitive force, not to analyze and deal with the forces. Represented
3、 by force of effort.3., according to the situation, or with the parallelogram rule, or with the triangle rule, or by the orthogonal decomposition rule, improve the purpose of force synthesis and decomposition, and reduce blindness.4. for equilibrium problems, the equilibrium conditions are F = 0, si
4、gma M = 0, the column equations are solved, and then discussed.5. for the change of equilibrium state, the problem of force change can be studied by analytic method or graphic method.Static learning problems can be divided into three categories:The use of force synthesis and the law of decomposition
5、.The balance and the change of the concurrent force.Balance and change of the fixed axis.Understanding the balance and balance conditions of objectsFor a particle, if the particle remains stationary or uniformly linear at the action of the force, i.e., the acceleration is zero, it is called a balanc
6、e. To balance the mass, there must be a sigma F = 0. If the orthogonal decomposition of each force, there are: Sigma FX = 0, sigma FY = 0.For a rigid body, equilibrium means that there is no translational acceleration, that is = 0, and there is no rotational acceleration, = 0 (stationary or even spi
7、nning), at this time: Sigma F = 0, sigma M = 0.It should be pointed out that when the object is balanced under three forces (non parallel forces), the following conclusions can be drawn according to sigma F = 0:The three forces will be concurrent.These three force vectors form a closed triangle.The
8、resultant force of any two forces must be equivalent to the inverse of the third forces.Analysis and procedure of force on an object(1) stress analysis points:1, clear the object of study2. Analyze the number and direction of force acting on an object or a node. If it is a connecting body or an over
9、lapping body, use the isolation method3, when drawing a large force line correspondingly longer4, each force marks the corresponding symbol (powerful must be famous), in English letters5 objects or nodes:6. Solve the dynamic equations of the column by orthogonal decompositionWhen the force is balanc
10、edWhen the force is unbalanced7, the force characteristics of some objects:8, the same rope on the smooth pulley or smooth hook, the rope on both sides of the force size is equal, when the more than three sections of rope knot at the intersection, each rope rope force size is generally not equal.(tw
11、o) stress analysis procedure:1, to determine the number of objects, and mapping: (gravity); contact force (elasticity and friction); field force (electric field force, magnetic force)2, the direction of judgment:Judge according to the nature of the force and the cause;According to the movement of th
12、e object to judge;A is judged by Newtons third law;B is judged by Newtons second law (in the direction of acceleration, the object is forced).Two. Basic methods and steps of solving kinematics problemsThe basic concepts of kinematics (displacement, velocity, acceleration, etc.) and the basic laws ar
13、e the basis for solving problems. They are the weapons that we understand problems, analyze problems and seek ways to solve them. Only when we have a profound understanding of concepts and laws can we solve all kinds of problems flexibly, but solving problems is a necessary link to deeply understand
14、 the concepts and laws.According to the basic concepts and laws of kinematics, the basic method and procedure for solving kinematics problems are shown(1) 2. You understand, sketch, clear the known quantity, unknown unknowns.(2) make clear the object of study. Select the reference frame and coordina
15、te system.(3) analyze the time, displacement, initial velocity, acceleration and so on.(4) apply the law of motion and geometry relation to establish the equation of solution.(5) solving equations.Three. The basic method of solving dynamics problemsWe analyze and solve dynamics exercises with the ba
16、sic concepts and basic laws of dynamics. Because of the complex dynamics, we classify the exercises according to different dynamics.1, the application of Newtons law to solve the problem,There are two basic types of this problem: (1) the known object is subject to the motion of the object; (2) the f
17、orce of the object is determined by the motion of the known object; there are many problems in the two basic problems.From the object of study, there are multiple objects with a single object.(1) basic methods of solving problemsAccording to Newtons law, the basic method of solving exercises isAccor
18、ding to the selected research object, determine the m.Analyse the force of the object and determine the force of the painting.Analyze the movement of the object and determine the a.According to Newtons law, the concept of force, the law and the formula of kinematics, the equation of solution is set
19、up.Solving equation.The checking, discussion.The above, the second and the third are the basis of solving problems. They are often interrelated and can not be separated.The problem of solving by using kinetic energy theoremThe theorem of kinetic energy is that the energy, force, displacement, kineti
20、c energy, velocity, mass and so on can be calculated according to kinetic energy theorem.What is the basic method to solve the problem by applying kinetic energy theorem?A displacement of selected objects and objects to specify m and s.Analyse the force of the object and combine the displacement to
21、make clear.Analyze the initial velocity of the object to determine the kinetic energy at the beginning.Then, according to kinetic energy theorem and equal column equation, the solution equation is checked and discussed.(example) as shown in Figure 4 - 5, the quality of the board is 3 meters long. Ob
22、ject mass. The coefficient of friction between an object and a board, the coefficient of friction between a board and a horizontal groundThe right end of the board is in a stationary state. The horizontal horizontal pull of the cow is now used. The object will slide on the wooden board. After 2 seco
23、nds (1), how much will the force F do? (2) what is the kinetic energy of an object? (M / S 2)The problem of solving by momentum theoremFrom the theorem of momentum, this theorem can be applied to impulse, force, time, momentum, velocity, mass, etc.The basic method of solving momentum theorem isSelec
24、t the object and a section of the process to define m and t.Analyse the force of the object to definite the impulse.The analysis of objects at the beginning and the end of the speed to clear at the beginning and the end of momentum.Then, according to the momentum theorem, the equations are establish
25、ed, the equations are solved, and the computations are discussed.example 8 the weight of 10 kilograms of heavy hammer from 3.2 meters high free fall hit the workpiece, hammer hit the workpiece after jumping 0.2 meters, hitting time is 0.01 seconds. Calculate the average striking force of the hammer
26、on the workpiece.The application of the law of conservation of mechanical energyThe formula of conservation of mechanical energy is known. It can be used to calculate kinetic energy, velocity, mass, potential energy, height, displacement, etc.The basic method of applying the law of conservation of m
27、echanical energy isThe selected system and a section of displacement are selected.Analyzing the external force, internal force and the work done by the system to determine whether the mechanical energy of the system is conserved.The analysis system of objects in the initial finalstate position and v
28、elocity to determine the initial finalstate machinery.Then, according to the equations of conservation of mechanical energy, the equations are solved and checked.Four. Basic methods of solving electric field problemsThe main problem of this chapter is the description of electric field property and t
29、he effect of electric field on charge. When solving a problem, it is necessary to find out several physical quantities describing the electric field property and study the law of electric field.1, how to analyze electric field, electric potential, electric field force and electric potential energy i
30、n electric field(1) first, the electric field studied is the electric field formed by those field charges.(2) find out the meaning of the symbols of the physical quantities in the electric field.(3) correct application of superposition principle (vector sum or scalar sum).The meanings of the quantit
31、y symbols are briefly described below:The positive and negative of the electricity only show the difference of the electricity, but not the size of the electricity.The electric field intensity and electric field force are vectors. When applying Coulomb law and field intensity formula, do not substit
32、ute the sign of electric energy,The size and direction should be determined by calculation. In space, the direction of field and electric force cannot be simply expressed by +, -The potential and electric potential energy are scalar, and positive and negative represent the size. When they are used t
33、o calculate, they can substitute their symbols, such as U is positive, q is negative, and so is negative, such as U1U20 and Q are negative.When the electric field work is positive or negative, the electric potential energy of the electric charge is correspondingly changed. When the WAB is positive (
34、i.e., the electric field force is positive work), the electric potential energy of the charge decreases; when the WAB is negative, the electric potential energy of the charge increases. Therefore, when applied, the symbol of the electric field force can be determined by replacing the symbols of each
35、 quantity. Of course, you can also use the size of the work, and then the electric field force and direction of movement to determine the positive and negative work. But the former can be directly compared with others.2, how to analyze the balance and motion of electric charge in electric fieldBalan
36、ce and moving charge in the electric field is a comprehensive knowledge about the mechanics of the electric field; Sichuan Xi? Comprehensive problem can be solved, to deepen understanding of relevant concepts and rules, improve the analysis, have a significant role in comprehensive ability problems.
37、 The analysis method of this kind of problem is the same as that of mechanical analysis:(1) determine the object of study (a charged body).(2) analyze the external force of charged body.(3) according to the analysis of the physical process, should pay attention to discuss various conditions, analysi
38、s of the implied conditions in question, this is the key to solving the problems.(4) according to the physical process and the known physical quantities, the proper mechanics law is chosen.(5) discuss the results.4 example in Figure 7 - 3 shows, if (triton) and (helium) vertical electric field direc
39、tion into the same deflection field, and in the case when the lateral displacement of their size ratio. (1) enter at the same initial velocity; (2) enter at the same initial kinetic energy; (3) enter at the same initial momentum; (4) enter the same accelerated electric field before entering.Analysis
40、 and solving of charged particles in the electric field electric force is far greater than the gravity, so gravity can be ignored. The charged particles in the deflected electric field are subjected to the action of the electric field force, which is similar to the motion of a flat throw, which move
41、s uniformly in the original velocity direction and accelerates uniformly at the transverse velocity. By using Newtons second law and uniformly accelerated motion formula(1) enter the electric field at the same initial speed V0, because E, l and V0 are the same, so(2) enter the electric field at the
42、same initial kinetic energy, Ek0, because E, l and MV2 are the same, so.(3) enter the electric field at the same initial momentum as P0, because E, l and MV0 are the same(4) the electric field of the particle is accelerated after the same accelerating electric field is accelerated and then enters th
43、e electric field(U1 for accelerating voltage)fromBecause E, l, and U1 are the same, the size of the Y is independent of particle mass and power, so:Note that in the ratio for lateral displacement of the Y, should first find the expression of Y, the condition, find out the Y and m, the particle mass
44、power ratio of Q, then list than the solution this is the general method of solving ratio.3, how to analyze the problem of parallel plate capacitor?Attention should be paid to the analysis of such problems(1) the parallel plate capacitor is open circuit in the direct current circuit, and the voltage
45、 between the two plates is the same as that of the appliance (or branch) connected in parallel.(2) if the capacitor is connected with the power supply and the switch is closed, when the two plate distance is changed or the two plate is facing the area, the two plate electricity is invariable, and th
46、e charged quantity of the polar plate is changed. If the switch is switched off, the distance between the two poles is changed and the voltage will be changed accordingly when the distance between the poles is changed or the two plate is facing the area.(3) the parallel plate capacitor is a uniform
47、electric field,The electric field intensity between the two plates can be discussed, and further discussion is made on the balance and transport of the charges between the two plates.4, the electric field and potential are analyzed by using the characteristics of the power line and equipotential sur
48、facePower lines and equipotential surfaces can visually describe field strengths and potentials. The number of electric lines drawn around the charge is proportional to the charge of the charge. The density and direction of the power line indicate the magnitude and direction of the electric field strength, the decrease of the potential of the power line, the equipotential surface, the vertical