Ask for help with questions about the high 3 physics total review

Physics, this thing, as long as you find the right model and learn the formula, you have to remember that it is a must, and then you can understand the origin of the formula, and when these are all done, you can try to do some typical questions, these questions will be explained carefully by the teacher, and then you will find more questions to do, do it first and then look at the answer, try to think about the problem with your own thinking, and then there are physics problems, mechanics problems, you must be able to draw more diagrams, and the function is to consider the process, ** how much work to do, and then kinematics This thing Draw the number line on the line Circular motion Understand the force Draw the force analysis on the line Electromagnetism is to memorize formulas, add drawings, and draw diagrams, electricity is to draw circuit diagrams, and then analyze, in short, physics is very dependent on mathematics, as long as you know mathematical models, it is very simple, physics problems do not have to do more, but you must be refined, and every time you do a problem, you have to learn the method, instead of thinking about how the number comes about, to understand the physical processes in it, and review questions, I am high 3, I didn't buy any questions, and I did all the papers issued by the teacher

1.First of all, the force analysis of the negative charge is carried out, and it is found that there is a force exerted by a uniform electric field, and there is a force exerted by the positive charge, because the direction of the two forces is different, but the magnitude is the same, so the negative charge is balanced at the D point, and f1=qe, f2=kqq r squared, then there is e=kq r squared.

2.The electric field strength of A and B is required here, and only the uniform electric field and the electric field excited by the positive charge can be considered.

First of all, understand the basic knowledge points and understand the basic methods. Start with sync exercises. The difficulty of the exercises is gradual. If you find it difficult to learn the knowledge points and methods on your own, you can find a teacher to tutor you individually.

f = horizontal direction using the momentum theorem.

ft-ft=mv

v = maximum velocity when f decreases and f = f.

At this time t'/(6-4)=(

t'=[(4-2)+6]×3/2-(

vmax=

During my internship, I found some common feelings among students, who felt that physics was the most difficult subject in high school. In fact, physics does have high requirements for students, so physics cannot achieve good results only by listening to lectures.

Physics must be learned well, mathematics cannot be left behind, mathematics is the basis of physics calculation, so, first of all, you have to have confidence, you have to believe that you will learn physics well, you don't understand, others may not understand; Secondly, it is necessary to lay a good foundation in mathematics; Again, it is the learning method you are more concerned about, and the learning method of physics generally has several steps: (1) Listen carefully in class and take good notes in class, of course, notes are not written by the teacher to memorize, focus on what you don't know, or don't quite understand. (No matter how difficult the content of the class is, you have to insist) (2) Find a time to review the notes taken in class, review the content of the day first, and then make breakthroughs in the notes on the day, there are many ways to break through, for example, ask the teacher directly, or ask the classmates around you, it is best to use your brain first, and find someone to ask for help if you really can't do it (3) For the notes you took that day, pick out the relevant exercises in the textbook or review reference book to practice well, and summarize some skills for doing questions, Write down the skills in your notebook as well, right next to the relevant notes.

There are several steps in the normal solution of physics, the first is of course to review the problem, and then you convert the language of the problem into physical language, that is, to draw sketches, build physical models, and then you list the relevant formulas to see what physical quantities are in the problem, what formulas need to be used, and finally the solution is the problem. I hope you have gained something after reading it, and I wish you success in the college entrance examination!

One of the things I feel the most is that I ask the teacher or classmates, ask if I don't understand something, and then write it down and make some annotations, look at it before the exam, in fact, you won't calm down and look at the questions before the exam, at this time, the annotations on your side are actually the most useful, you will find that you have a closer relationship with teachers and classmates, and at the same time, your physics grades have gradually improved.

Reading Books Reading Books If you really want to read the content carefully, the definition is very important. After reading a section, do the exercises for one section.

You should look at the example questions, and the notes in class should be done well, and then you will find that the high school physics problems have a fixed routine, and the format of the solution is very regular. The two upstairs said really reasonable, although it is good to ask questions, but the questions are not good, you have to learn to listen to the questions, and it is best to listen to the teacher when explaining to other students

The first thing you need to do is to think about the common types of questions yourself, and then find the answers, don't develop the bad habit of looking at the answers, and try to ask teachers and classmates as much as possible.

Listen to the teacher in class. Listen carefully. There are many more questions. Buy a good, but not a rare review material!

,,, talk about this kind of thing,,, anyway, most of the physics problems are related to force, so let's talk about it after doing the force analysis well

(m1-m2)v0-m2v2 = m1v1 ；[m1-m2)v0-m2v2]/m1 = v1

m1+m2)v0²=m1v1²+m2v2²

m1+m2)v0²=[(m1-m2)v0-m2v2]²/m1+m2v2²

m1(m1+m2)v0²=[(m1-m2)v0-m2v2]²+m1m2v2²

m1(m1+m2)v0²=(m1-m2)²v0² -2m2(m1-m2)v0v2+m2²v2²+m1m2v2²

m2(m1+m2)v2²-2m2(m1-m2)v0v2+[(m1-m2)²-m1(m1+m2)]v0²=0

m2(m1+m2)v2²-2m2(m1-m2)v0v2+(m2²-3m1m2)v0²=0

m1+m2)v2²-2(m1-m2)v0v2+(m2-3m1)v0²=0

b²-4ac=4(m1-m2)²v0²-4(m1+m2)(m2-3m1)v0²

4v0²[(m1-m2)²-4(m1+m2)(m2-3m1)]

4v0²[4m1²]

16m1²v0²

v2=[2(m1-m2)v0±4m1v0]/2(m1+m2)

v2=-v0 ②v2=[(3m1-m2)/(m1+m2)]v0

The results show that the velocity of m2 does not change after the collision (the velocity of m2 before the collision is -v0, not v0), and it is unreasonable to give it away.

The results show that if m1=m2, v1=-v0, and v2=v0 the velocity of the two is unchanged, the reverse bounces.

Known: m1, m2, v0, find v2

The first one is the conservation of momentum, right? m1v0-m2v0=m1v1+m2v2 or m1v0+m2v0=m1v1+m2v2?

The second is the conservation of energy m1v0 + m2v0 = m1v1 + m2v2

But regardless of whether your above equation is correct or not, there are only two unknowns, v1 and v2, two equations, which should be able to be solved.

It's just that since it is a quadratic equation, there may be two solutions, whether or not one should be discarded according to the meaning of the topic.

For the first equation, m1(v1-v0) = m2(v2- or as above + v0).

The second equation, m1((v1) 2-(v0) 2) = m2((v2) 2-(v0) 2).

m1(v1-v0)(v1+v0)=m2(v2-v0)(v2+v0)

v1+v0=v2+v0 or v2-v0 as above

v1=v2 or v2-v1=2v0

Then according to the first formula, join, the solution can be obtained.

There is also the case of v1 = v0.

You're one equation away. The pre-collision encounter velocity is equal to the post-collision separation velocity, and then solve it with this.

(1) First look at T1, because the trolley is stationary, the ball is balanced by force, and can only receive the rope AO, BO tension and its own gravity, if there is a pull force in the BO direction, the tension can be decomposed into vertical downward and horizontal left directions on the two directions, obviously the horizontal direction of the component has no other force to balance, then the ball is only subject to gravity and AO tension, then t1 = mg;

2) In the same way, when the trolley accelerates to the left, the ball has a leftward acceleration, that is, the net force of the ball is to the left, and obviously BO must provide a pulling force before there can be a leftward force. The tensile force of Bo is decomposed into two components in the horizontal and vertical directions, the horizontal direction provides leftward acceleration for the ball, and the vertical direction is offset by the pulling force of AO, then T2=mg+F (the component of Bo in the vertical direction), so T2>mg.

The answer is D

Pick D. When at rest, the ball is subjected to two forces: T1 straight up and mg straight down. At this point, t1 = mg.

When accelerating to the left, the ball is subjected to three forces: T1 vertically upward, mg vertically downward, and TB downwards to the left (the pulling force of the B rope to the ball). Tb is decomposed into two components to the left and down, three forces in the vertical direction, t2=mg+tb component in the vertical direction, so t2>mg.

f2 is balanced with the gravity of the person, so f2 does not change;

For F1, F1 = Mg Cos A, and A is the angle between F1 and gravity Mg.

Since the angle becomes smaller after lying down, the force on F1 is greater when sitting.

You can make it clear.