Draft lecture on Newton's second law 1 1, teaching material analysis
Newton's second law is the core law of dynamics, the foundation of classical mechanics, and the content that must be mastered in further learning other parts of knowledge such as heat and electricity. So Newton's second law is the central content of this chapter, and it is also the teaching focus of this chapter. In order to make students understand Newton's second law naturally and harmoniously, the "change of motion state" before this section plays a connecting role. To strengthen students' understanding of the first law; Enlightenment is to make students understand the content of Newton's second law qualitatively through the analysis of examples. On the basis of the previous section, this textbook summarizes Newton's second law which quantitatively describes the relationship between acceleration, force and mass through experimental analysis and computer induction. Summarizing physical laws from experiments is an important way for us to understand objective laws. Because this experiment involves three variables, A, M and F, we use the method of controlling variables to study: first, determine the mass of the object and study the relationship between acceleration and force; Then determine the force and study the relationship between acceleration and mass. This method will be applied to the study of gas state change law, capacitance of parallel plate capacitor and resistance of metal conductor in the future. Control variable method is also a common method for us to study natural and social problems. Through teaching, students can learn to analyze experimental data, get two commonly used methods of experimental conclusion-list method and image method, and understand the advantages of image method in data processing: intuition, reducing error (taking the concept of average), image transformation, from A-M diagram (curve) to A- 1/M diagram (straight line), and image transformation is also used in verifying Bohm's law. According to the above analysis, we know that the teaching purpose of this class is not to let students know the content and significance of experimental conclusions and laws, but to let students know how the conclusions are drawn; What kind of scientific methods and means were used in drawing conclusions; How to control experimental conditions and physical variables, and how to express physical laws with mathematical formulas. Let students follow the historical footprint of their discovery of physical laws and experience the thinking methods of scientists.
Through this lesson, students should remember the expression of Newton's second law; Understand the physical meaning of each physical quantity and formula; Understand the research methods based on experiments, and express the physical laws with mathematical formulas through measurement, demonstration, induction and summary, so that students can appreciate the simple beauty of physical laws.
This lesson focuses on successful demonstration experiments and computer analysis of data. This is the core of this course and the key to its success.
Second, teaching methods and learning methods.
This class adopts "synchronous regulation" mode, based on computer-aided demonstration experiments, and combines knowledge teaching with scientific method education.
According to the principle of holistic function of system theory, holistic function is greater than the sum of all elements. Physics knowledge, methods, abilities and scientific attitudes are all elements of teaching. If these elements are organically linked and promoted, the effect of physics teaching will be better and more conducive to the improvement of students' quality. In the "synchronous regulation" mode, knowledge learning, method mastery, ability training and scientific attitude of seeking truth from facts are organically combined, which is based on the principle of the overall function of the system.
Furthermore, according to the teaching-oriented and learning-oriented principle in teaching theory, teachers' tasks are to set goals, organize teaching activities, control the process of teaching activities, improvise, remove obstacles, and recognize and respect students' subjective status. "Synchronous adjustment" mode not only pays attention to the role of teaching, but also puts teachers in the position of "adjustment". At the same time, we should pay more attention to students' main role, consciously set up the environment of teaching activities, let students participate in the design of experiments, ask questions while demonstrating, let students observe and think, and then draw conclusions from experimental data, so as to mobilize students to actively participate in teaching activities to the maximum extent. Slow down the speech in the difficult part of the textbook to give students enough time to think and discuss. For example, from the A-M image, guess that A is inversely proportional to M, and then draw the A- 1/M diagram, and get the correct conclusion. Let students learn knowledge, master scientific methods and cultivate the spirit of exploration, creativity and scientific attitude of seeking truth from facts in teaching activities, so as to achieve the prescribed teaching objectives and the best results.
Third, the teaching procedure.
1. Introducing questions into the new curriculum
An object on a smooth horizontal plane is accelerated by horizontal tension, which guides students to analyze the qualitative relationship among the mass, acceleration and tension of the object and encourages students to guess that they are directly proportional, inversely proportional and not directly proportional. Then it is pointed out that in this class, all of us will explore the quantitative relationship among the three, thus leading to this subject-Newton's second law. The purpose of this introduction is to improve students' interest in learning and enthusiasm for exploration.
2. Design the experimental scheme
After introducing the topic, inspire students to think: How do we study the relationship among F, M and A? Guide students to determine M through experiments and study the relationship between A and F; Then determine f, study the relationship between a and m, and finally get the quantitative relationship between them. Due to the lack of Newton's second law experiment in the teaching material (compulsory one, People's Education Edition) (it is difficult for the clamp to hold two thin lines at the same time; Because of the elasticity of the line, the car can't stop before the recoil, so I designed an experiment to explore the relationship between A, F and M with computer assistance, as shown in the attached figure. The width L of the shutter passes through the photoelectric gate t 1 and t2 respectively, and the distance between the two photoelectric gates is S. When the slider passes through the photoelectric gate, the photoelectric gate generates a pulse, which is amplified by the transistor in the timer, input from the LPT port of the computer, and calls the computer to interrupt the timing to calculate the time, and then uses the formula.
Lecture Notes on Newton's Second Law 2 I. Teaching Contents
Force produces instantaneous effects, one is deformation, the other is the change of motion state, that is, acceleration. The third section of the first chapter of the compulsory book has qualitatively introduced the deformation effect of force, and quantitatively given the relationship between spring elasticity and deformation. This section "Newton's second law" is a quantitative study of the relationship between force and acceleration. Because high school mechanics is a system based on Newton's law, Newton's second law is the core of Newton's three laws. The second section of the textbook "Changes in the motion state of objects" plays a connecting role, enabling students to deepen their understanding of Newton's first law and qualitatively understand Newton's second law through examples. In this section, Newton's second law is obtained through experimental quantitative analysis. Three variables are used in the textbook, and the laws of physics are studied by controlling variables, that is, the changing relationship between the other two physical quantities is studied by keeping one quantity unchanged, and then the changing relationship between the other two quantities is studied by keeping the other quantity unchanged. Then we can get the relationship between the three, which is a very important research method and will be used in the future knowledge of capacitance and resistance. It is a good material to cultivate students' ability.
In order to simplify the research, we first study the situation under the action of a single force, and then use the knowledge of the synthesis of the previous forces to solve the situation under the action of multiple forces, and classify the objects learned in junior high school and senior high school as the special cases of Newton's second law. This will help students to further understand the equivalence of synthesis, make their knowledge more systematic and help them master Newton's second law systematically.
This section is the key content of this chapter, the key content of the whole mechanics part, and even the key content of the whole high school physics. The methods and ideas it solves are often used in the study of thermal and electrical problems.
This section focuses on the understanding and application of Newton's second law, and the difficulty is the physical connotation of this law.
It should be pointed out that in this experiment, the car was placed on a smooth horizontal surface to do this experiment. As we all know, it is impossible to find a smooth horizontal plane. Therefore, in the actual experiment, it is necessary to use an inclined plane to balance the friction of the wooden board or the air cushion guide rail to do the experiment. This kind of operation not only increases the operation difficulty of the demonstration experiment, but also increases the difficulty for students to understand the experiment. In order to solve this problem better, this experiment can be simulated by computer in this course. For example, we can use the software of "Simulated Physics Laboratory" of Jinkelong Company to make a sports animation courseware to simulate the movement of a car to study the relationship between A, F and M. Practice has proved that the effect is very good and the difficulty of this section is effectively reduced. After students have a certain foundation, they will come back to understand why they don't use physical objects here for the first time and how to do it with physical objects, further consolidating the scientific ideas and scientific research methods obtained from Newton's second law.
Second, the teaching objectives
According to the requirements of the syllabus, the specific content of the teaching materials and the cognitive characteristics of senior one students, the following teaching objectives are put forward:
1, knowledge goal: According to the experimental results, we can deduce the relationship between a, f and m, understand and master the content and mathematical expression of Newton's second law, and define the unit n of force.
2. Ability goal: I can understand the expression of Newton's second law under the action of various forces, initially master the methods and steps of solving Newton's second law, and pay attention to the instantaneity and vector of Newton's second law in concrete application.
3. Thinking quality goal: enable students to learn and master the method of studying the relationship between multiple physical quantities by using controlled variables, and solve problems through equivalent viewpoints.
Third, teaching methods:
1, experimental guidance and exploration: The physical examination syllabus clearly requires students to have five abilities: understanding, reasoning, comprehensive analysis, solving physical problems with mathematical knowledge and practical ability. This section is just a good teaching material to cultivate these abilities, so the method of experiment-guided exploration is adopted. In the experiment, the teacher properly guided the key steps, and obtained that when M is constant, A is directly proportional to F, and when F is constant, A is inversely proportional to M, thus guiding students to draw Newton's second law, and then extending it to the situation that the relationship between A, F and M is in balance under the action of various forces.
2. Combining lectures with practice: When discussing several problems that should be paid attention to when solving problems by applying Newton's second law, let students analyze the problems. Teachers should pay attention to finding students' questions at any time or deliberately giving wrong answers, organizing students to analyze the causes of errors in time, organically combining students' subjectivity with teachers' dominance, strengthening relevant knowledge in time and improving the accuracy of mastering knowledge.
Fourth, the teaching procedure:
1, introduction of new curriculum
(1) Looking back on the contents of the previous section, we qualitatively draw the conclusion that A is related to both F and M. So, what is the quantitative relationship among them? Guide students to make bold guesses and improve their participation awareness and interest in learning.
(2) Introduce the research method of studying three variables-control variable method.
(3) Research scheme: Experiment. We use computer simulation experiments to get relevant data and draw a conclusion.
2. the relationship between a and f when m is constant.
(1) experimental device: explain clearly the experimental device, the research object and the application of external force.
(2) How to keep the quality unchanged: experiment with two cars with the same quality.
(3) How to measure the acceleration? According to the motion law of an object with an initial velocity of 0, under the same condition of t, a∝s can meet the requirement of measuring A by measuring S.
Simulation experiment 1: the car mass is 0. 1kg, trolley 1 pull 0. 1N, trolley 2 pulls 0.2N and starts to move at the same time. Observe the displacement relationship between two balls in any time period, and draw a conclusion according to the experiment: a ∝ f.
{Example 1}, P89-EX2 (1)
3. the relationship between a and m when f is constant.
Simulation experiment 2: Both cars are 0. Under the tensile force of 1N, the mass of trolley 1 is 0. 1kg, and the mass of trolley 2 is 0.2kg. Observe the displacement relationship between the two balls at any time, and draw the conclusion according to the experiment: A ∝1m.
{Example 1}, p89-ex2 (3)
4. Newton's second law
Based on the above two experimental results, the relationship between a, f and m is obtained, and then Newton's second law is introduced.
(1) Contents: A. Written expression: B. Mathematical formula C. Definition of unit n of force (2) Understanding:
First, the vector
B, instantaneity
(3) Application
First, Newton's second law under the action of multiple gravity
B, the equilibrium state is a special case of Newton's second law.
{Example 3}, P89-EX2-5
5. Summarize the contents of this section.
This section is based on the qualitative research on the relationship between A, F and M in the previous section, and obtains the quantitative relationship between them by using the experimental results, that is, Newton's second law, which is simply applied on the basis of understanding. This section should focus on the understanding of the law, and the application of the law will gradually deepen in the future practice.
6. Task P89-EX2 (2) (4)
Five, blackboard writing
1. Research scheme: Experiments were used.
2. the relationship between a and f when m is constant. a∝F .
3. the relationship between a and m when f is constant. A∝ 1/ meter.
4. Newton's second law
(1) Contents: a. Written expression: b. Mathematical formula: a ∝ f/m. F=maC, and definition of force unit n: 1N= 1kg.m/s2.
(2) Understanding: vector instantaneity
(3) Application: Newton's second law under the action of multiple gravity.
The equilibrium state is a special case of Newton's second law.
5. Homework P89-EX2 (2) and (4)
Lecture Notes on Newton's Second Law 3 I. teaching material analysis
Newton's second law is the core law of dynamics, the central content of Newton's law of motion in the fourth chapter, and the teaching focus of this chapter. On the basis of the experimental results in the second section, this section analyzes Newton's second law and gives a concrete and quantitative answer to the rate of change of the speed of a moving object, that is, the relationship between acceleration and force and mass. Newton's second law closely links the motion and force of an object through acceleration, making the first three chapters form a whole, which is an important tool to solve mechanical problems. This law is a bridge between force and movement, so the teaching of this lesson is in a very important position in the whole textbook.
Second, the key points and difficulties
In determining the focus and difficulty of this section, I think students should not only master the content of Newton's second law, but also pay attention to the importance of students' understanding of the application of Newton's second law in real life and how to use it to solve practical problems. Therefore, the key point is to understand and apply Newton's second law; The difficulty lies in correctly understanding the connotation of Newton's second law through simple application.
Third, the teaching objectives
According to the requirements of the course and the actual needs of students, determine the three-dimensional objectives of this course.
1, knowledge and skills
Master the literal content and mathematical expression of Newton's second law; Understand the meaning and causality of each physical quantity in the formula; Know Newton's definition, the unit of force in the international system of units; Will use Newton's second law formula to do related calculations.
2. Process and method
Based on experiments, the relationship between the acceleration of an object and its mass and external force is summarized, and then Newton's second law is summarized. Cultivate students' generalization ability and analytical reasoning ability.
3. Emotional attitudes and values
Infiltrate the research methods of physics through the regular exploration process; Experience the charm of physical methods; From cognition to experiment, summarize the laws of applied physics, let students experience the joy of success and establish confidence in learning physics well.
Fourth, teaching methods and learning methods.
"You can't teach anything, but you have to teach well." Senior one students lack creativity, their ability to create new theories by using existing knowledge is weak, their knowledge is not very accurate in the learning process, their mathematical reasoning ability is weak, and their ability to summarize laws according to experimental data is not strong. Although the mathematical expression of Newton's second law is simple and perfect, it is not difficult to remember. However, for students in Chengbu Miao Township in remote areas, it is difficult to fully and deeply understand the meaning and relationship of physical quantities in the law and firmly grasp the physical significance and broad application prospects of the law. What's more, physics is a science based on experiments and closely related to life. Therefore, I think that the teaching method of combining explanation, discussion and analysis should be adopted in the teaching process. Starting from students' cognitive psychology, the teaching procedures of introducing questions, exploring independently, analyzing and discussing, communicating and cooperating, drawing rules, consolidating exercises and strengthening applications should be adopted. Let students combine observation with questioning, independent inquiry with communication and cooperation, cultivate students' reading thinking ability, and explain, guide, correct and analyze appropriately according to students' cognitive effect, so as to deepen the physical connotation of Newton's second law mathematical expression.
Teaching process of verbs (abbreviation of verb)
(1) Guide: First, watch the video materials such as the rocket ascending to the sky, the athlete Liu Xiang 1 10 meter hurdle start and the Olympic women 100 meter start with multimedia, and then guide the students to discuss what is the factor that determines their speed change, that is, acceleration? Then ask the students to review the conclusion of the last experiment. What is the relationship between the acceleration of an object and its external force and mass? Objective: Through the analysis of real life phenomena, to stimulate students' interest and cultivate students' ability to find problems, and to complete the introduction of Newton's second law inquiry task by discussing the relationship between acceleration and external force and object quality.
New curriculum:
First, guide students to read the textbook independently and answer the following questions:
L, how should the content of Newton's second law be expressed?
2. How to express its proportional formula?
3. What do these symbols mean?
4. What is the unit of each physical quantity? Among them, how to define the unit of force "Newton"?
(Let the students discuss and analyze related problems and memorize related knowledge) Transition: Above we studied the situation that an object is acted by a force. When an object is subjected to several forces, how will the above law be expressed?
After students' discussion and analysis, the teacher came to the conclusion that the acceleration of an object is directly proportional to the resultant force of external forces and inversely proportional to the mass of the object, and the direction of acceleration is the same as that of the resultant force.
(Objective: To cultivate students' ability to discover general laws)
Example exploration and consolidation exercises
Discuss the relationship between A and F, and judge which of the following statements is correct? Why?
A, only when the object is stressed, the object has acceleration.
B, the force is constant and the acceleration is constant.
C, the force changes with time, and the acceleration changes with time.
When the force stops, the acceleration disappears.
E. The object moves in a straight line with uniform acceleration under the action of external force. When the resultant force decreases gradually, the speed of the object also decreases gradually.
The acceleration of an object is constant and must be acted by a constant force.
Teacher's summary: Force is the reason for the acceleration of an object. Force and acceleration of an object are vectors, instantaneous and independent. Newton's second law is derived from the case that an object moves in a straight line with uniform acceleration under the action of constant force, but the principle of independent action of force can be extended to several cases of force action and applied to a certain moment under the action of variable force.
Understanding of Newton's Second Law
1, the following understanding of Newton's second law expression F=ma and its deformation formula is correct: () a, from F=ma, the resultant force acting on an object is directly proportional to its mass and inversely proportional to its acceleration; B, from m=F/a, it can be known that the mass of an object is directly proportional to the resultant force it receives and inversely proportional to the acceleration of its movement; C, from a=F/m, it can be seen that the acceleration of an object is directly proportional to the resultant force and inversely proportional to its mass; D, from m=F/a, we can know that the mass of an object can be obtained by measuring its acceleration and resultant force.
2. In Newton's second law formula F=kma, the statement about the proportional constant K is correct: () A is equal to 1 B in any case, and the value of K is determined by the mass, acceleration and force. The values of c and k are determined by the units of mass, acceleration and force. D in the international system of units, the value of k must be equal to 1. Teacher's summary: defining power. It is one of the characteristics of physics to express physical laws in simple mathematical language, but we should know its corresponding text content and significance.
Application of Newton's second law
Put a wooden box with a mass of 40kg on the ground, and push the wooden box with a force of 100N at an angle of 37 with the horizontal, as shown in the figure, in order to make the wooden box move at a constant speed. What is the acceleration of the wooden box if it is pulled upward at an angle of 37 from the horizontal with this force? (Take g= 10m/s2, SIN 37 = 0.6, COS 37 = 0.8) (3) Class summary and homework: omitted.
Six, teaching postscript
Breakthrough methods to highlight key points and difficulties;
I did it through regular analysis and targeted exercises. Of course, I also need to experience and understand in the course of study and application in the following courses. It is clear that students should deeply understand and master Newton's second law and apply it to solve problems in life. Avoid students from turning living rules into dead formulas.
Teaching problems to be considered:
The new curriculum standard of physics in senior high school requires students to have a more accurate understanding and skilled application of Newton's second law. However, for our remote Chengbu Miao township, whether it is teaching resources or students' quality, it is very difficult to fully meet the requirements of the new curriculum standards in teaching.
Draft lecture on Newton's second law 4 (1) teaching material analysis
Newton's law of motion is based on the knowledge of force and motion, and further studies the relationship between force and motion. Newton's law of motion is the basis of classical mechanics. A series of important physical laws such as kinetic energy theorem and momentum theorem can be deduced from Newton's law of motion. Newton's law of motion is also an important basis for studying heat and electromagnetism. Therefore, this chapter occupies a very important position in mechanics and physics as a whole, and is the focus of physics teaching in middle schools. Newton's second law is the core law of dynamics, and it is the focus and central content of this chapter.
(B) teaching content, teaching material system and teaching objectives
After Newton's first law, the textbook in this chapter has arranged a section on "Changes in Motion State", which plays a connecting role. It not only deepens Newton's first law, but also makes students realize that force is the cause of acceleration and mass is the measure of inertia. It also paves the way for studying Newton's second law, making students realize that the acceleration of an object is determined by force and mass, and have a qualitative understanding of the relationship between them.
In this section, the relationship between acceleration and force, acceleration and mass is studied by the experimental method of controlling variables, and then Newton's second law is summarized by combining the two. Then, Newton's second law is extended from the special case of an object subjected to one force to the general case of multiple forces, from the case of an object subjected to a constant force to the case of an object subjected to a variable force, and further emphasizes the vector and instantaneity of Newton's second law.
According to the above analysis and the requirements of the syllabus in this section, combined with the actual situation of students, the objectives of knowledge teaching are determined as follows:
1. Know the content and expression of Newton's second law, understand the meaning of Newton's second law, and apply Newton's second law to analyze and solve related problems.
2. Understand the vector and instantaneity of Newton's second law.
3. Know the definition of the unit of force "Newton".
In the teaching of this course, scientific method education should also be infiltrated. By studying the relationship between acceleration and force and mass, students can master the control variable method. In the process of summarizing Newton's second law, let students experience the scientific research method of experimental research, analyzing data and summarizing laws, and cultivate students' ability of experiment, observation, analysis, induction and generalization in this process.
(3) Teaching methods
According to the teaching content of this class and the actual situation of students, the teaching method adopted is: based on demonstration experiments, with activities to guide students to explore laws as the main line, and teaching-oriented and learning-oriented teaching ideas throughout the teaching activities.
In this course, the qualitative experiment of the teaching material is changed to the quantitative experiment by using the air cushion guide rail, and the experimental data are analyzed by using images, so that the relationship between acceleration and force and between acceleration and mass can be expressed more intuitively, which makes students more confident to obey the conclusions drawn from the experiment and is helpful for students to master Newton's second law. Although this experiment is a demonstration experiment (limited to experimental conditions), from the design of the experiment to the control of experimental conditions, the measurement and analysis of experimental data, and the generalization and summary of laws, we all pay attention to mobilizing students' enthusiasm, guiding students to take the initiative to participate, and fully embodying students' dominant position.
(4) Teaching procedures
1. Introduce new courses
By reviewing the qualitative relationship between acceleration and force and mass, students can make it clear that the acceleration of an object is related to force and its mass. Further question: What is the quantitative relationship between acceleration and force and mass? This leads to the topic.
In this way, the introduction of new lessons is simple and clear, and to the point.
2. New curriculum teaching
(1) Design experiment
① Design an experimental device.
Guide students to design experimental devices from three aspects: experimental object (slider moving along air cushion guide rail), experimental source (heavy object providing tension) and experimental effect display (photoelectric door, computer timer).
② Design the measurement method.
In the experiment, it is necessary to measure the mass, tension and acceleration of the slider.
The mass of slider and counterweight is measured by balance (before class).
The tension on the slider can be regarded as equal to the gravity of the suspended heavy objects (buckets and weights) (the mass of the suspended heavy objects is much smaller than that of the slider).
The acceleration of slider is the focus and difficulty of measurement, and it is also the focus of guiding students to design experiments in teaching. First of all, let the students make it clear that we can't measure the acceleration directly, but should measure the related physical quantities to find the acceleration. In the experiment, it is easy to measure the displacement S and time T of the slider movement, and then calculate the acceleration with the formula. This requires that the displacement s and the corresponding time t of the slider should be measured in the experiment.
③ Design research methods.
When guiding students to learn ohm's law in junior high school, review the methods used in studying the relationship between current, voltage and resistance, and make it clear that the control variable method is needed in studying the relationship between multiple physical quantities. In this experiment, the control variable method is used to study the relationship between acceleration and force and the relationship between acceleration and mass respectively.
Instead of introducing experimental devices and methods to students, under the guidance of teachers, teachers and students design experimental devices and methods according to experimental purposes, so that students can change passive acceptance into active design and turn bystanders into people. Students have a clearer understanding of experimental devices, experimental methods and experimental processes. This design fully mobilized students' enthusiasm, played the main role of students, and cultivated students' innovative ability.
(2) Experimental exploration
Keep the mass of the slider unchanged, change the tension of the slider by changing the gravity of the hanging weight, measure the acceleration of the slider under different tension, establish an A-F coordinate system by multimedia projection demonstration, and draw a line drawing method according to the measured data. From the image, when m is constant, a ∝ f.
Keep the tension constant, change the mass of the slider and measure the corresponding acceleration. A-M coordinate system is established by multimedia projection, and curves are obtained by tracing points according to measurement data. The curve leads students to guess that the acceleration may be inversely proportional to the mass. Further enlightening students, in order to verify the conjecture, it is necessary to draw an image of A- 1/m, and then let students establish the coordinate system of A- 1/m according to the above method, draw a line connecting points, and get a straight line passing through the origin, thus proving that the conjecture of A- 1/m is correct and finding the quantitative relationship between acceleration and mass.
The method of summarizing physical laws with image analysis experimental data is one of the difficulties of this course, and it has just started for students. Therefore, in teaching, teachers should draw A-F images through multimedia projection and explain to students how to establish coordinate system, choose scale, trace points and connect lines. Then according to this method, students can draw an image of A- 1/m and find out the relationship between acceleration and mass.
(3) Summarize the law
Guide students to synthesize the above two experimental conclusions, summarize the content and expression of Newton's second law, define the unit of force "Newton" by discussing the value of proportional coefficient K, and then illustrate the relationship between acceleration and force direction through experiments, emphasizing the vector nature of Newton's second law.
3. Consolidate and improve
Consolidate Newton's second law through examples and exercises, and make students realize the instantaneity of Newton's second law through thinking and discussion.
4. Course summary
Knowledge summary: Review the content of Newton's second law, and emphasize its vector and instantaneity. It shows that Newton's second law is the core of dynamics, which determines the relationship between force and motion, and it can explain why objects do this or that motion, and emphasizes the importance of Newton's second law.
Scientific method summary: Summarize the control variable method, design the experimental method according to the experimental purpose, analyze the experimental data with images, and summarize the physical laws.