Damn physics, physics problems, tears

In fact, the difficulty of both mechanics and electricity in physics is about the same, so if you want to learn it well, you should do what I say.

1.Despise him in your heart. Thinking that he is very studious is called suggestion in psychology.

2.If you don't learn electricity well, most likely you won't even understand electrical circuits now. You won't be able to deal with complex circuits, and this problem should be the first thing you solve.

As long as you can understand all the complex circuits, then learning electricity is half the battle.

3.On the basis of understanding the circuit, you have to memorize each formula, sort out a ** by yourself, and write all the formulas on it.

4.The circuit will be read, and the formula will be known, so you need to practice more. At first, you can look at the formulas you have compiled yourself to do the problems, and gradually you will understand it.

5.For the current electrical experiments, there are mainly two of them: voltammetry resistance measurement and small bulb electric power, and these two are required for the high school entrance examination. Make a lot of effort to get these two understandings right.

Good luck learning.

I watched "Towards Tsinghua University and Peking University" I didn't know how to read electricity at the beginning, I watched it all night, and then electricity became the simplest existence in physics.

In fact, the most important thing is to calm down, find more classic circuit diagrams to analyze, when looking at the circuit diagram, a branch of a branch D walk, practice a few more to improve quickly.

Regarding electrical work and resistance, as long as the size and voltage of each resistance are accurately calculated, it is basically done (the voltage is proportional to the resistance, which is very easy to use, and there is no need to consider the internal resistance in junior high school, everything is very simple).

I benefited a lot from learning electricity in junior high school to high school, and now I feel it deeply.

Actually, I didn't do very well in physics at the beginning, because I chose liberal arts, but I had to take the physics exam in my sophomore year of high school. At that time, I didn't know what was going on, the newly invited physics old man in our school had a very strange temper, but since he came, my physics grades have gone up! Physics is not only about doing questions, but also about memorizing some concepts, and listening to lectures well and doing the questions given to you by the teacher!

Very important. Formulas are also important! There are so many formulas for acceleration, and there are so many transformations, you have to do the problem while experiencing it, and you have to memorize the formula!

To learn a subject, you must first be interested, in fact, physics is very interesting, electricity is also very simple, it is estimated that you are electric power or the right hand rule did not understand, don't worry, everyone has this process, the past is good, you must not rush for quick success.

The multiplier is pretty good.

Physics knowledge is everywhere in life, and you should pay attention to it. While learning physics, it is important to pay attention to the connection with the phenomena in real life, especially to pay attention to hands-on practice.

Longmen tutoring two-color notes, this set of books is very good, especially for science, I suggest you take a good look, it will be of great help.

This classmate, don't hate physics, it's not wrong, think about whether you can leave physics in your life, to learn physics well, one is to practice, the second is to drill, the third is to ask, and the fourth is to summarize.

You must be serious in class, and the high school entrance examination is a heavy foundation.

You'd better read the book first and then buy a copy of "Complete Interpretation".

On the first floor, people want to take the high school entrance examination, which is a junior high school.

Is there a junior high school in Longmen?。。。 I haven't seen it.

In fact, I think I should do more questions to cope with the high school entrance examination, and then listen to the teacher's lecture

Sort out the formula by yourself, finish the workbook issued by the school, and listen to the teacher.

Complete Interpretation" is a good material, so I'll use it.

Question iodine. The foundation is good.

Because the center of gravity of the lever is at the geometric center of this stick.

Point A is (15-8) from the left end of the lever, 2=A is 15 from the center of gravity of the lever

When point A is used as the fulcrum.

It can be obtained according to the balance of leverage.

f1×l1＝f2×l2

400n×4m=500n×l2

Solution: l2=

When the person is away from point A, the plank will start to warp.

Since it is symmetrical.

The center of the plank is 4 meters from the left end, which is 4 meters from A.

Moment balancing. g (person) * x = g (wood) * 4

x = m is the person warping when he is away from point a.

For the lever problem, A is the fulcrum when lifted, and if the gravity of the person is the driving force, the resistance is the gravity of the plank, which acts on the center, that is, 4m away from the point A.

According to the principle of leverage equilibrium, 500N*L=400N*4m can obtain L=

It's just from the far left.

When the lever is balanced, the dynamic moment is the resistance moment, when it is cocked, when the person starts from point A and walks to the left from point A lm, the plank will begin to warp, the kinetic moment = the gravity of the person * l 500 l, the resistance moment The gravity of the plank 8 2 = 400 * 4, according to the principle of lever balance 500n * l = 400n * 4m

It can be obtained that l = is the person warping when he walks to the left and is meters away from point a.

No, because mirrors are not specular, they are diffuse.

No, because the acceleration of the fall of the person above is greater than the acceleration of the rise of the person below, and the acceleration of the ab whole and the acceleration is downward.

I didn't understand the title, do you mean that you want to use sound waves as energy** and convert them into power? In that case, I think it works in theory, as long as there is always sound that can provide you with energy.

Same as 3, both are waves.

The logic is wrong, isn't the perimeter changed after the fold?

Isn't the reaction force on the magnet downwards when the iron rises? Where does the anti-gravity of the magnet come from? Inward?

No, of course I mean the absence of wind, isn't the air on Earth rotating with the Earth? So the hot air balloon will move with it, and it would be troublesome to say that the air does not rotate with the Earth, and the linear velocity of the Earth's equator is supersonic.

To put it mildly, light has wave-particle duality. According to the person, everything has its own wavelength, and with the same velocity, the greater the mass, the smaller the wavelength. (including macroscopic matter), the algorithm forgot, and the electron microscope uses electrons with wavelengths much smaller than light waves, so they can see smaller objects clearly.

1. No, first of all, the mirror is not 100% reflective, there will be a loss of energy, and it cannot be absolutely parallel, it is unstable, as long as there is a slight deviation of the light, it will shoot out.

2. No, if B forcibly lifts A when he does not step on the ground (assuming that he can do this), then he will be subjected to A's reaction to him, which will make B accelerate his fall, and it is impossible for A to lift B at this time, because part of B's momentum is caused by A, that is, B is larger than A's momentum.

3. It depends on the situation to use sound as a driving force to propulsion, the premise of being able to propelle is that the force is greater than the resistance, and even if it is greater than the resistance, there is also the mass of the object, and the effect is not obvious if the mass is large, because the inertia is large.

4. Light can be used as power, in fact, there is this, but it is not possible to achieve the speed of light, at least not at present, because first of all, the object has to accelerate, and the mass of the object becomes larger when the speed of the object increases, so that the acceleration is more difficult, this problem Einstein has calculated, if it is good, the maximum speed in the end is close to the speed of light, which is also under the premise of sufficient energy.

5, this is to find the law by yourself, list the formula and prove it slowly, of course, so many mathematicians are not stupid, not everyone is wrong, and they are all wrong in getting the same number.

6. I really don't know what you're talking about this question.

7. No, because people have inertia on the earth itself, it's just that we move with the earth, so we can't feel it. And when we are in the air, we are also affected by gravity, and this force becomes a centripetal force, which makes us move with the earth.

Asking for advice is not the same as asking questions, and it is often difficult to get the answers you want if you ask questions that you don't understand.

Even in the most ideal case, a beam of light cannot be preserved in a limited area made up of only mirrors. Like hitting a billiard ball, photons can sometimes bounce back when they hit an electron, sometimes they bounce back partially, sometimes they are completely absorbed and subsequently converted into the internal energy of the mirror to increase their temperature, or they may pass through it without hitting anything. So the situation you have in mind is unattainable.

Photons have momentum, and when an object emits light in one direction, the object gains momentum in the opposite direction and moves it forward, but this momentum is so small that it is completely imperceptible to the human senses when it is expressed in the velocity of the object.

If you doubt what I said, you can borrow a high school textbook and take a look, it's much better than stumbling around in the --- of the Teaching Edition of High School Physics Elective 3-5 Chapter 17 Section 2 The Particle Nature of Light.

According to the characteristics of uniform speed movement, S vt 1 2AT