New Curriculum Middle School Physics Academic Exam Review Guidance Answer 20

Suke version of the eighth grade physics second semester final review practice - calculation questions.

1 The stone pillar placed on the horizontal ground, the height is, the cross-sectional area is, the mass is 150kg, g takes 10n kg and finds:

1) the gravity of the stone pillars;

2) the density of the stone columns;

3) The pressure of the stone pillar on the horizontal ground

The Wenchuan Da ** on May 12, 08 touched the hearts of hundreds of millions of Chinese. In the post-earthquake disaster relief work, scientific search and rescue methods are very important. There is a tool called "air mattress", which is not much larger than a pillow, has a non-slip mesh on the surface, and when it is not inflated, it can be stuffed into it as long as there is a gap of 5 cm.

1) The surface of the air cushion has a non-slip reticulation, is this to increase or reduce friction?

2) In a search and rescue process, when the air pressure in the air cushion is increased to 8 atmospheres with a gas cylinder, the mat of the "air drum bulge" jacks up the floor slab, and the contact area between the air cushion and the floor slab is 1250cm2, how much is the force of the air cushion on the floor slab? (Take 1 atmosphere as 1 105pa).

3 In order to increase the students' knowledge of national defense, the students of Class 8 (1) of Yanghu Middle School visited a certain type of submarine in the East China Sea Fleet The hull of the submarine is made of high-strength special steel plates, and the maximum diving depth can reach 350mThe total volume of the submarine is 15 103m3, there are water tanks on both sides of the boat, and the cross-section of the submarine is shown in the figure Change the self-weight of the submarine by filling the water tank with water or discharging it outward from the water tank, so that it sinks or floats (the density of sea water is 1

03 103 kg m3, g takes 10n kg).

1) When the tank is not filled with seawater, the total weight of the submarine is 106 n, at this time, what is the volume of the submarine floating on the surface of the sea to discharge the seawater?

2) What is the minimum weight of the tank that should be filled with human seawater in order for the submarine to be completely submerged?

3) What is the reason why the hull of a submarine is made of high-strength special steel plates?

4 An irregular solid object, mass 55g, put in a beaker filled with pure water, sink to the bottom, drain the water. Then add salt to the beaker and stir until the object is suspended. g=10n kg).

1) the buoyancy of the object in pure water;

2) The volume of the object:

3) The density of the brine when the object is suspended.

Here you go, hope it works for you.

1. Improve students' scientific literacy for all students;

2. From life to physics, from physics to society;

3. Pay attention to the penetration of disciplines and care about the development of science and technology;

4. Pay attention to science and advocate the diversification of teaching methods;

5. Pay attention to the orientation of evaluation reform and promote the continuous development of students.

Junior high school physics mainly reviews five major areas: sound, light, force, heat, and electricity.

Sound, the main thing is to remember those values, such as: the listening range of the human ear, the speed of propagation in the air at room temperature, etc.

Light, the main thing is to remember those optical path diagrams, and the speed of light is best to remember as well.

Force, learning is mainly force analysis It is recommended that you review the wheel and practice several force analysis. The pressure should also be looked at, and it is also the content of the high school entrance examination. Buoyancy is a formula that can be used.

Just remember the definition of friction (analysis is essential). The key to leverage is force analysis and which formula, you can practice a few less.

The key to heat is to do a few exercises than the heat capacity.

First of all, the circuit diagram should be mastered (you should be able to draw a circuit diagram, and you should also master the characteristics of the current and voltage of the series and parallel circuits). The second is the experiment, which is generally combined with the circuit diagram, and you have to learn to analyze the circuit diagram. The key to calculations and experiments is to memorize those formulas.

Ohm's law is to be memorized. Magnetism is generally combined with electromagnets, and it is necessary to master the solenoid winding and magnetic induction effect, as well as the working principle of generators and motors. The home circuit is mainly to analyze the circuit, and there is no problem if the circuit diagram is learned.

Junior high school physics is basically just that, I hope you will study hard according to this "list" method! (Personally, I don't support the tactics of the sea of questions, so it's good to be able to master this type by doing a few typical questions.) Good luck with your studies!

What I said downstairs has been more detailed, so I won't be verbose, and simply talk about a few review aspects.

The test questions in electricity are about 10-15 points, and if you study hard when you first learn, then there is no problem.

There will also be some questions in the mechanics test, with a score of about 5-10 points.

For those questions of buoyancy, the test questions will generally be out, 1-2 multiple-choice questions, 1-2 fill-in-the-blank questions, and the final big question may have 1, but there is no need to worry too much, the questions will not be too difficult, and the score is about 10 points.

In a question that is leverage, the score is about 5 points, and the question of leverage is relatively not difficult, so you can take a closer look. Hope.

I just finished the high school entrance examination, I am from Heilongjiang, I don't know if you are **, but junior high school physics is roughly divided into several large parts, electricity, optics, mechanics (including pressure, pressure, buoyancy, gravity, levers, pulleys and other simple machinery), heat, magnetism, and energy with a very small score (nuclear energy or something). When reviewing in electricity, first look at the definition, especially the current characteristics of series circuits, the law of equivalent resistance, etc., which are easy to test in the experiment, and can not be bad, as well as Ohm's law (you will definitely do this, as long as you learn it) and electric power (love to calculate and the key points in the big experiment) is the most difficult (in fact, you will enter the door, you will do a lot of questions without getting started, and you will find your own teacher if you make up the class, and you will find your own teacher to make up the class, and you will talk about experience), there is a home circuit in electricity, which is not difficult, But be sure to listen to the teacher (seriously, kid!). We generally have 2 or 4 points out of the fault question connection, the basic knowledge fill in the blank or something.

Heilongjiang Harbin, this electrical credit value is the largest, mechanics and optics are basically flat, mechanics does not have many problems, that is, friction some experimental problems are not easy to do, and there are some force analysis, the foundation is weak will be proficient in the third year of junior high school, if you are not familiar, believe me, practice slowly, it is not difficult, but your focus on the high school entrance examination may not be the same as ours. Buoyancy experiments are also calculated, buoyancy calculations probably won't be problematic, but you still have to do more, long knowledge, buoyancy experiments are relatively basic, occasionally there will be innovative questions, but the level can be done well, will not ask. Gravity is simple and stress-free in junior high school.

There are several rules for simple machines (e.g., the balance condition of the lever, the equation of the pulley), all of which are within the acceptable range. The slope of Harbin is not a big problem, and the lever pulley occasionally comes out. In mechanics, the equilibrium of two forces is sometimes experimented.

There is a very important law of cattle, the most important thing!! Don't ignore it!! It's easiest to test in mechanics.

Pressure pressure is strong, air pressure is also the focus of the calculation experiment two-pronged, occasionally there are problems, or more practice. Optics must be a little difficult to learn at the beginning, but looking back at the simple is not good, if you think it is difficult is not good to learn, occasionally there are some experimental problems, drawing is basically necessary, drawing questions are just a few things, circuit diagrams, optical drawing, mechanics. By all means.

Experiments are nothing new, practice makes perfect, kid! What molecular kinetic theory here in thermal science is a small case, the specific heat capacity is the key, there must be more calculations and fewer experiments, and the calorific value is basically only calculated when the real exam is made. Magnetism is mostly electromagnetism, and there are few pure magnetisms, and there are basically no experimental questions.

I don't know if you have energy, but we have it, but it's very superficial.

That's basically these, I hope it will be useful to you, although the two of us may not be a province, but junior high school physics is just a few pieces, even if there is a deviation, the focus is not much worse, but you must remember that physics must do a lot of questions, especially experimental questions and the final big calculation, accumulate question types and experience. Physics is not mathematics, do more problems and open the door to basically barrier-free, physics is to experience, no matter what level you are, as long as you don't learn, the accumulation of experience will not be worse than the best, believe me.