Urgently ask for junior high school physics, please explain in detail Thank you junior high school p

If you lose points because you are careless in the questions you can do, then I am speechless! Try to improve it.

If you really can't do it, there are two reasons: one is that there are too few types of questions, note that I am talking about the type of questions here rather than the amount of questions, and it is stupid to do similar questions often! Ostensibly you know everything, so buy new reference books with a lot of topics.

The second is that you lack the idea of solving the problem or you do not summarize it, but just passively accept it and do not think and summarize after solving a problem! It is recommended to ask those students who are good at physics about their problem-solving ideas.

And look at the good notes made in those class notes.

It's not bad to do more difficult problems, like any competition, and many of the answers are very ingenious and incisive.

In fact, boys who study physics are more talented, and some people can get high scores just by attending classes! It's because I understand it thoroughly.

Dizzy. I never review physics studies. Why?

Tell you to learn thoroughly, tell you a theorem to gnaw thoroughly. How to gnaw, to analyze the principle, how to touch and push, does not have to be a question. Got it.

If you want to go to the Orsay, it's best to read a book.

In fact, it is the easiest, you learn deeply, if you finish all the high school studies, and then do junior high school, pediatrics.

I think according to your current situation (the ability to understand is very good, and the understanding is also very high, but it is easy to forget, and the second part of the lecture forgets the front), the main reason should be that there are too few questions, and the theoretical things cannot be applied to practice. It is recommended to do more exercises, and then think carefully about what is going on, and gradually your physics academic performance will improve!

In fact, she said this because she thinks that you already have the strength to score high, and what you really lack is confidence, you always see high scores as pressure, and you can turn high differentiation into motivation, and I say that these hopes will help you, because at this time, even if you find a more powerful and senior teacher to teach you face-to-face, it is useless, at this time, you can only believe in yourself, because the potential of people is great, you have to have confidence in yourself, so that you can score high, and you will not disappoint your teacher's expectations of you So now the most important thing is for you to have faith in yourself, and that's all I can do for you.

I'm sure you didn't really understand what the teacher said, and if you understand what you digested, it's not so easy to forget.

Mark the physical quantities (with a pencil) on the question first, and then substitute them into the formula one by one.

The premise is that the formula is familiar.

Physics in junior high school teaches relatively little content.

The first step is to understand the concept.

Secondly, pay attention to comprehension in the composition of the questions, do a few more similar questions, and master them.

Finally, pay attention to summarizing your mistakes.

Believe that once you master the method, progress is fast.

Junior high school... Me too...

Let's do more questions.,It's very useful.。。。 That's how I am.

Although I despise it, it's still fun to do some experiments.

Curcuma is to do more questions. I don't know if it's suitable for you, but I think that if I don't do physics for a day, my brain will be much dumber.

1) The phenomenon that will occur after the water boils is that the water vapor will flush the rubber plug out of this process, and the chemical energy of the fuel will be converted into internal energy, and the internal energy will be converted into mechanical energy through work.

2) Observe the experimental device and find that the test tube is filled with metal, and the function of this metal is to ensure personal safety.

Molecular gap: 10 ml of water + 10 ml of alcohol < 20 ml.

Molecular movement: A drop of ink is placed in a bottle of water, and it slowly spreads around until the bottle contains as much ink everywhere.

Option A First, the whole method A and B systems move at a constant speed, the resultant external force is zero, and the gravity g of B and B is balanced with the rope tension f, f=49n; Then study a, the friction force f and the rope tension f are balanced, f = f = 49n, so a is selected.

Start oa*g copper = ob*g iron I call copper m1 iron and iron m2.

Put in water. On the left is OA* (M1G-F buoyancy) and on the right is OB* (M2G-F buoyancy).

Opening both sides is equivalent to judging the buoyancy of OA* copper and OB* iron.

Buoyancy is directly proportional to volume.

That is, to determine which is larger than oa*v1 and ob*v2.

Whereas, the density of copper is greater than that of iron.

and vp=m oa*m1=ob*m2 hence oa*v1(m2g-f2)ob

If you don't understand, you can ask and continue.

Because copper is denser.

Previously, the equilibrium state means that the moments of the two parties have been balanced, and this satisfies the moment equation.

If both sides are put into water at the same time, the volume of water they drain is the same (because they are the same size) because the density of copper is greater than that of iron. So at this time, the buoyancy of the water is the same, and the mass of the copper is larger, so the copper block will fall. Select B

If it is connected in series first, the rated voltage of A is 10V, and the rated voltage of B is (U-10)V and then paralleled, U'= (u-10)v, ua = (u-10)v=16 25*10v=

u'=, u=, ratio.

If it is connected in parallel first, in series, similar method, you get u=10v,u'=

i) If it is connected in parallel first and then in series.

U=10V,RB25,IB

then the first is normal

r A 20 contradictions.

ii) If it is connected in series first and then in parallel.

iNormal u (rA+rB).

There is u'rA A+rB).

u'rB u (rA+rB).

then B r A.

u'/u=4/9

Because w=mgh=gh=fs

You know, the direction and magnitude of the force are determined, plus the force acting on the object, and the above formula holds.

Here g is your understanding of f, the force acting on the object in the vertical direction is gravity, gh is the displacement in the vertical direction as you understand it, h is the displacement in the vertical direction, and the displacement caused by gravity g acting on the object.

Because it is moving at a uniform velocity, f=g=mg

The first thing to do is to determine if this is an elevation under completely ideal conditions.

According to the comparison of the actual work of 30000 and the theoretical work of 21000 joules, it can be seen that this is not the work done under ideal conditions, and 9000j of energy is lost, including the work done to overcome inertia.

Therefore, the work used here is not the total work but the useful work, that is, the work done to improve the goods, because the power given in the question is also to improve the power of the goods. Hope.

s is the distance, in this problem, the magnitude of h is the distance raised, s f is equal to the gravitational force g on the object,,, so in the problem, g is used instead of f, and h is used instead of s,,, which is the reason.

72km H = 20m s, engine power output: P = FV = 5 10 20W = 100KW

1) Since there are 4 ropes in the bi or pull it, so f=g 4=

2) There are four ropes pulling it, so the hunger rises 1m in length to multiply the rotten Hui Dan by 4 times, so. l=4m

Between the two movable pulleys of the bridge banquet, a movable pulley is added, because the movable pulley can be divided into several, so as to save effort and effort.

The liquid pressure formula p= gh, p and known, g takes 10 and substitutes the value to obtain h=5m

According to the liquid pressure formula p= gh, it is obtained by directly substituting the data.