.read-contentp*{font-style:normal; font-weight:100; text-decoration:none; line-height:inherit;}. read-contentpcite{display:none; visibility:hidden;}

The next few days passed in a drowsy state, and before I knew it, I myself had become decadent. Pen Fun Pavilion wWw. ｂiquge。 info Teacher Zhou also directly removed my position as class president, which also made me a lot easier.

"Stand up, hello teacher. ”

"Hello everyone, I am your new physics teacher Zhang Feng, then I will take your physics in the next half semester, if you have no problems, then we will come to class." ”

He is Zhang Feng, the new physics teacher, I also only found out today, I heard that it is a high-achieving student specially recruited by the school, very capital, very profound, but very young, I heard Zhang Hailong say, he was going to go to the doctorate, but then I don't know why I didn't take the exam, and I don't know how to come to our school.

"The students turned to page 42 of the book, and what they talked about today is. Mechanical energy] 1. Energy 1 Definition: An object can do work over it, we say that the object has energy 2 Classification: An object with energy may be moving to do work, or it may remain stationary 2. Kinetic energy 1. Definition: The energy that a moving object has due to motion 2. Factors affecting the magnitude of kinetic energy: (1): The mass of the object (2) The velocity relationship of the object: the greater the mass of the object, the greater the velocity, the more kinetic energy it has3. Characteristics: motion (all moving objects have kinetic energy) 3. Gravitational potential energy 1, Definition: The energy that an object subjected to gravity has due to being lifted is called gravitational potential energy2, influencing factors: (1) the mass of the object (2) height 3, relationship: the greater the mass of the object, the higher it is lifted, the more gravitational potential energy it has4, characteristics: height 4.elastic potential energy 1 definition: the energy that an elastic object has due to deformation2 relationship: the greater the elastic deformation of the object, the greater the elastic potential energy it has3 factors: the magnitude of the elastic deformation 5. Mechanical energy1 Definition: kinetic energy and potential energy are collectively referred to as mechanical energy units: joules2 An object may have both kinetic energy and potential energy, such as an object flying in the air3The sum of kinetic energy and potential energy is the total amount of mechanical energy of the object45 Mutual conversion between kinetic energy and potential energy6Rolling test: Ascending process: Kinetic energy is converted into gravitational potential energy Descending process: Gravitational potential energy is converted into kinetic energy (rolling test) (single pendulum test)7Single pendulum test: Ascending process:

Descent process:

1. During the movement of the satellite: from far to near:

From near to far:

If only kinetic energy and potential energy are converted into each other, then mechanical energy is conserved [internal energy] 1. The basic content of molecular kinetic theory: 1. Matter is made up of molecules 2. Molecules are in constant motion, and the higher the temperature, the more intense the molecular motion 3. There is an interactive gravitational force and repulsion between molecules 2. Internal energy 1. Molecular kinetic energy: the energy of energy due to molecular motion (the higher the temperature, the more intense the molecular motion, the greater the kinetic energy) 2. Diffusion phenomenon (1) Definition: When different substances are in contact with each other, the phenomenon of entering each other is called diffusion phenomenon, the higher the temperature, the faster the diffusion process (2) Substance: The diffusion phenomenon proves that the molecules are constantly moving irregularly, and also proves that there is a gap between the molecules, which can occur between the three states (3) Common diffusion phenomenon

3. Definition of molecular potential energy: The energy that a molecule has due to the intermolecular force is called molecular potential energyThe molecular force: (1): The intermolecular force includes gravity and repulsion, and they exist at the same time (2): When the distance between molecules is too large, gravity plays a major role, and the distance between molecules is too small, and repulsion plays a major role (3): Examples of molecular gravity:

4. Internal energy (1), definition: the sum of the kinetic energy and potential energy of all molecules of an object is called the internal energy of the molecule (2), the internal energy of the same object is related to temperature: when the temperature of an object increases, the internal energy increases but the internal energy increases, the temperature does not necessarily increase (3), gas expansion work test: (1) light the alcohol lamp, the alcohol burns, and the chemical energy is converted into internal energy (2) the water vapor washes the plug away, and the internal energy is converted into mechanical energy (4), the method of changing the internal energy of the object: 1. Work done: 1. Essence: work is the transformation of energy 2, The outside world does work on the object, and the internal energy of the object increases; the object does work on the outside world, and the internal energy of the object decreases (gas expansion) (gas expansion does work test) 2. Heat transfer: 1. Substance: the transfer of energy 2. Conditions: there is a temperature difference 3. An object absorbs heat, and the internal energy must increase, and the temperature does not necessarily increase (work and heat transfer are equivalent in changing the internal energy of the object, and the internal energy of an object increases, it may be that the outside world has done work on the object, or it may be that the object has absorbed heat) 3. Specific heat capacity 1, Experimental conclusions(1) Water and kerosene with the same mass and initial temperature absorb the same heat, and the final temperature of kerosene is high, because the specific heat capacity of kerosene is small (2) Water and kerosene with the same mass and initial temperature release the same heat, and the final temperature of water is high (3) Water and kerosene with the same mass and initial temperature, the temperature rises by the same degree, and the water absorbs more heat, because the specific heat capacity of water is larger 2. Definition: The heat absorbed or released by a unit mass of a certain substance when the temperature rises or decreases by one degree Celsius is called the specific heat capacity of this substance 3. Unit: joules per kilogram of Celsius J/kgcj/kgk4, the significance of the specific heat capacity of the substance: c water = 4.2x103j/kg.c The physical meaning of C is that the heat absorbed by the temperature of 1kg of water is 4.2x103J5 when the temperature of 1kg rises 1C, and the specific heat capacity is a property of the substance, which has nothing to do with the mass, volume, temperature, shape, and heat 6, and the specific heat capacity of water is large.

4. Heat engine 1, definition: a machine that converts the internal energy after fuel combustion into mechanical energy 2, classification: gasoline engine and diesel engine 3, work: (1) a working cycle of a gasoline engine includes an suction stroke, compression stroke, power stroke, and exhaust stroke Only the power stroke does external work, and converts internal energy into mechanical energy, while the three strokes of suction, compression, and exhaust are completed by relying on the inertia of the flywheel (2) In a working cycle, the piston reciprocates twice, and the flywheel rotates two wheels, but only does external work once 4, Comparison of compression stroke and work stroke

Difference 5: Comparison between gasoline engine and diesel engine: gasoline engine, diesel engine inhales the substance of the cylinder, the mixture of air and gasoline, pure air structure, spark plug, fuel injector, ignition method, ignition type, compression ignition type

6. Rocket: It is a kind of heat engine, a machine that converts chemical energy into mechanical energy, and the rocket uses a rocket jet engine 5, fuel calorific value 1, fuel combustion: converts chemical energy into internal energy 2, calorific value definition:

3. Unit: J/kg or J/M34, the physical meaning of the calorific value of the fuel: the calorific value of kerosene is 4.6x107J/kg The physical meaning is 5, the heat released by fuel combustion Q = mq6, the calorific value of the fuel has nothing to do with the quality and combustion, half of a bottle of kerosene is used, and the remaining kerosene density, specific heat capacity, and calorific value are unchanged 7, the efficiency of the furnace. ”

We can all understand these things, but it's not the same thing to understand them, and when they come out of her mouth, they feel buzzing in my head when they hear it.

"1. Multiple choice questions: If only one of the options in the following questions matches the question, please fill in the code of the option in parentheses.

1. In the four examples shown in Figure 1, the refraction of light is "

"So who's going to answer this question next?"

We all meditated and thought, in fact, it was just a mess of paste, I was good at math, and I usually carried it back in this room, and when I was about to say the solution, it really couldn't work.

"Teacher, let me answer. "This is Gao Xiu, a member of the physics study committee, but he is known as a geek in junior high school and learning physics.

"According to your explanation, as shown in the figure, mirrors can reflect light, and so can glass, and this phenomenon will be reflected with all luminosity, and I think the answer to this multiple-choice question is b. ”

"This classmate said it well and hit the nail on the head. I believe that this multiple-choice question is difficult for all of you here, so what about this application question?......"

Gao Xiu then began to decompose: "Teacher, I think it should be like this......"

We have to admire Gao Xiu's ability to explain, after a class, three big questions, four small questions, none of which can stump Gao Xiu, but Mr. Zhang Feng's ability to solve problems can not help but let us admire, my physics grades are relatively average, and then look at my table mates, I don't know anything at all, I still have to learn from Ma Man.

To combat piracy and support genuine copying, please read the latest content on the Internet. Current User ID: , Current User Name: