Senior one (1) teaching goal physics teaching plan requires model essay 1 article.
I. Knowledge and ability:
1, know the definition and direction of centripetal force, and know the function and source of centripetal force through examples.
2. Understand what factors are related to the magnitude of centripetal force through experiments, preliminarily master the formula of centripetal force and calculate it.
3. Knowing centripetal acceleration and his formula, we can use Newton's second law to analyze the centripetal force and centripetal acceleration of uniform circular motion.
4. Experience the formation of centripetal force and centripetal acceleration's concept, and boldly express your understanding of related issues.
Second, the process and method:
Through centripetal force theory analysis to experimental exploration, students' literacy and ability to guide practice with theory are cultivated.
Third, emotional attitudes and values:
Cultivate students' ability to observe life and think about life phenomena, and at the same time cultivate students' scientific literacy of bold analysis and exploration, as well as the objective materialism spirit of respecting experiments and practice.
Teaching focus
The establishment of the concept of centripetal force and the experimental exploration of centripetal force are the key points of teaching.
Teaching difficulties
It is also difficult to establish the concept of centripetal force and explore the magnitude of centripetal force through experiments. Through simple examples and grouping experiments, we can strengthen our perception and break through the difficulties.
training/teaching aid
1, 16 sets of balls, strings and smooth boards.
2. Small hammer 16 pairs.
3. 16 centripetal force demonstrator.
4. courseware.
teaching process
First, the introduction of new courses.
Watch the video: China's Zhao Hongbo and Shen Xue won the gold medal in the figure skating competition in the 2006 Winter Olympics with wonderful performances, winning glory for their country. What action can Shen Xue's action in the video be approximately regarded as? (Student answer: uniform circular motion), what is the reason why its motion state has been changing? (Student answers: If it is strong, it will produce (acceleration). In this lesson, we will discuss the characteristics of resultant force and acceleration of objects moving in a uniform circle.
Centripetal force and centripetal acceleration.
Second, the definition of centripetal force induced by students' experiments
Guide students to make use of small balls, thin lines and smooth transverse plates in their hands to construct a simple uniform circular motion, so that students can bear the force on the small balls and get the characteristics of the resultant force on the objects with uniform circular motion: always pointing to the center of the circle, thus leading to the definition of centripetal force.
Blackboard writing: centripetal force.
1. Definition of centripetal force: An object moving in a uniform circle will be subjected to an equal force that always points to the center of the circle.
Third, students observe the direction of centripetal force.
Then guide the students to observe and analyze that the direction of centripetal force is always changing, which is a variable force but always points to the center of the circle and is perpendicular to the speed direction.
Blackboard writing: Centripetal direction: always pointing to the circle, and the speed direction is vertical.
Fourth, guide students to analyze the role of centripetal force. Because the direction of centripetal force and speed is always vertical, centripetal force does not do work and does not change the speed. Only by changing the direction of speed can the centripetal force be obtained.
Blackboard writing: The function of centripetal force: Do not change the size of speed, only change the direction of speed.
5. Guide students to analyze the source of centripetal force through three typical questions.
Analyze the force on the object and explain the source of centripetal force.
The object moves in a uniform circular motion with the turntable and the object moves in a uniform circular motion with the drum.
Writing on the blackboard: the source of centripetal force: centripetal force can be provided by a certain force such as gravity, elasticity and friction, or by their combined force or a component of a certain force.
Sixth, experimental exploration: the size of centripetal force
Question: What factors are related to centripetal force?
Guide students to do experiments with two small hammer balls and experience roughly by feeling. Students can speak freely after they have their own opinions through experiments and discussions. )
Students guess that the centripetal force is related to the mass m, radius r and angular velocity ω of the object.
(If students speak V, they can be guided to get the overlapping part of ω and V from the formula v=ωr)
Further guide students to guess the quantitative relationship. Students may guess that centripetal force is directly proportional to mass, radius and angular velocity. Teachers should not judge yet.
Question: Can the three quantities be changed at the same time in the experiment?
Student: No, we should keep other variables unchanged and change one variable, which is the control variable method.
Experimental device: centripetal force demonstrator.
Introduction structure:
Explain the working principle: the ball presses the baffle outward, and the reaction force of the baffle to the ball points to the rotating shaft, providing centripetal force for the ball to make uniform circular motion, and the two forces are equal. At the same time, the force of the ball pressing the baffle makes the other end of the baffle compress the spring sleeved on the shaft, and the number of compressed squares of the spring can be read from the scale to show the centripetal force.
Demonstration operation: how to realize control variables?
Emphasize the precautions:
Students divided into groups and got the following results:
① Relationship between F centripetal force and mass: ω and r are constants. Take two balls to make mA=2mB for observation: (students read) FA=2FB.
Conclusion: centripetal force f ∝ m
② Relationship between F centripetal force and radius: M and ω are constants. Take two balls to observe rA=2rB: (students read) FA=2FB.
Conclusion: centripetal force f ∝ r
③ the relationship between f centripetal force and angular velocity: m and r are constants, so ωA=2ωB observation: (students read) FA=4FB.
Conclusion: Centripetal force F∑ω2.
Induction: According to the above experimental results, we can know that the centripetal force required for an object to make a uniform circular motion is directly proportional to the square of the mass, radius and angular velocity of the object. But we can't draw a general conclusion from one experiment and one measurement. In fact, we need to make a lot of measurements, choose more sophisticated instruments and carry out a lot of experiments, but we can't finish them all. The experiment that students have just done shows that the greater M, R and ω, the greater F; If the experiment is slightly improved, such as the small experiment introduced in the textbook, and a spring scale is added to measure F, a general conclusion can be drawn. We can also design many experiments to come to this conclusion, which shows that this is a conclusion with * * *. By measuring the values of m, r and ω, we can know that the magnitude of centripetal force is F=mrω2r.
Blackboard writing: centripetal force: f centripetal force =mω2r=mv2/r
We know that the resultant force will inevitably produce acceleration, and the centripetal force is actually the resultant force of an object doing uniform circular motion. What is the acceleration caused by this force?
Seven, according to Newton's second law, centripetal acceleration is deduced.
Writing on the blackboard: centripetal acceleration
1, centripetal acceleration size: a=F centripetal force/m = ω 2r = v2/r = ω v.
a=4π2r/T2=4π2rf2
Question: What is the direction?
Blackboard writing: centripetal acceleration's direction: the same as the centripetal force, always pointing to the center of the circle.
Thinking: Is uniform circular motion uniform or non-uniform?
Student: No, because the acceleration is not constant. The direction has been changing.
Writing on the blackboard: centripetal acceleration's physical meaning: a physical quantity describing the direction of speed.
Consolidate in time
A light rope with a length of 0.5m is tied with a small ball with a mass of 2kg at one end and fixed at the other end. The ball moves around a fixed point at a speed of 4m/s on a smooth horizontal plane. Please calculate the centripetal force and centripetal acceleration of the ball.
Course summary
1. Knowledge content: (see blackboard writing)
2. Experimental method: control variable method.
3. Physical thinking: guess first and then explore, from qualitative to quantitative.
Model essay for physics teaching plan of senior one (2) Chapter 1 Description of motion +0. 1 Particle reference system and coordinate system teaching plan.
I. teaching material analysis
The first paragraph of this textbook states the goal of the whole textbook, which is to study "how to describe the mechanical motion of objects". The concept of coordinate system is clearly abstracted from the reference system at the beginning of the textbook. The guiding ideology is to emphasize the general scientific method, that is, to abstract the actual problem into a physical model first, and then describe the model with mathematical methods to find the solution.
In order to study the change of object position, we must first solve the problem of position determination. The textbook regards "objects and particles" as a knowledge point, which shows that particles are aimed at objects, and actual "objects" all "occupy a certain space". In the usual exercise process, "the exercise situation of different parts is different", which "brings difficulties to describe the exercise". The key to solving the problem is "Can a point replace an object?"
The "Global Positioning System" in the "Scientific Walking" column is an extensible content, followed by further research questions, such as "Where is this locator in which city in China?" What other information can you get from the display screen? ".The purpose of doing this is to make students form the habit of diligent observation and thinking, and improve their ability to acquire knowledge independently. These questions are not compulsory courses for all students.
Second, the teaching objectives
1, know the concept of reference system. Knowing that the same object chooses different reference frames, the observation results may be different.
2. Understand the concept of particles, know that it is a scientific abstraction, and know that scientific abstraction is a general research method.
Third, the focus of teaching
1. How to choose a frame of reference when studying problems?
2. Understand the concept of particles.
Fourth, teaching difficulties.
Under what circumstances can an object be regarded as a particle?
An analysis of the learning situation of verbs (abbreviation of verb)
Our students belong to parallel classes and there is no experimental class, so there is a gap between the existing knowledge and the experimental level. Some students have a certain foundation in stress analysis and exercise, but their comprehensive application is difficult and needs to be explained in detail.
Sixth, teaching methods.
1. Learning plan guidance: See the following learning plan.
2. The basic links of the new teaching: preview inspection, summing up doubts → situation introduction, showing objectives → cooperative inquiry, intensive reading teaching → reflection and summary, in-class inspection → issuing guidance plans and arranging preview.
Seven, preparation before class
1. Students' learning preparation: preview the relevant chapters of the textbook and initially master the basic ideas and methods of applying Newton's laws of motion to solve problems.
2. Teachers' teaching preparation: making multimedia courseware, previewing learning plans before class, exploring learning plans in class and expanding learning plans after class.
Class schedule: 1 class hour
Eight, the teaching process
(1) Preview the inspection and summarize the doubts.
Check and implement students' preview, understand students' doubts, and make teaching targeted.
(2) Scene introduction and display objectives.
When studying a problem, the factors that have little influence on the result are often ignored. Some physical models are often established, which is a scientific abstraction. Have you ever been exposed to such a physical model before?
Such as: smooth horizontal surface, light spring.
All these factors are neglected, such as friction and spring mass, which have little influence on the research problem. Today we are going to build a new physical model-particles. Particles, and complete the following questions:
Design intention: lead in step by step, attract students' attention, and define learning objectives.
(3) Cooperative inquiry and intensive teaching.
1, objects and particles
Fill in:
(1) A particle is a point with nothing but an object.
(2) Whether an object can be regarded as a particle is related to its size and shape?
(3) Can cars be regarded as particles when studying the movement of cars on straight roads? Can the car be regarded as a particle when studying the wheel rotation of this car?
(4) The nucleus is very small, can it be regarded as a particle?
(5) The path taken by a moving particle is called the motion of the particle; Is a straight line, called linear motion; This is a curve called.
* * * Note: A particle is a point without shape and size, and it has all the mass of an object. This is a scientific abstraction, that is, grasping the main characteristics and ignoring the secondary factors must be analyzed in detail. If the difference in the shape and size of an object and the motion of various parts of the object is secondary or invalid in the problem we study, we can regard it as a particle. For example, when we study the characteristics of a car moving on a straight road, the size and shape of the car and the differences in the movements of various parts of the car are secondary, and the car can be regarded as a particle. Studying the rotation of the wheel is to study the movement of the upper part of the car, so the car can't be regarded as a particle. For example, the nucleus is so small that you can't treat it as a particle when studying the interaction between protons.
2.( 1) frame of reference: In order to describe the motion of an object, the object selected as a standard is called a frame of reference.
(2) Different reference frames are selected to observe the same movement, and the observation results will be different.
For example, if you describe the same movement and choose different reference frames, the observation results will be different.
For example, a moving car chooses the ground as the reference system. If the driver is selected as the standard, the car is stationary. ...
(3) Summary: The frame of reference can be selected arbitrarily, but the principle of selection should make the movement and description as simple as possible. For example, it is simpler to study the motion of objects on the ground and choose objects moving on or relative to the ground as the reference system than to choose the sun as the reference system.
3. Coordinate system
If the object moves along a straight line, in order to quantitatively describe the position change of the object, we can take this straight line as the axis, specify the origin, positive direction and unit length on the straight line, and establish a linear coordinate system.
Generally speaking, in order to quantitatively describe the change of object position, it is necessary to establish an appropriate coordinate system on the reference system.
Pay attention to the following points in teaching:
The (1) coordinate system is fixed relative to the reference system.
(2) Three elements of coordinates: origin, positive direction and scale unit.
(3) the position of the coordinate particle.
(4) Describe the position change of the particle with the change of coordinates.
(4) Reflection and summary, classroom test.
Teachers organize students to reflect and summarize the main contents of this lesson and conduct classroom tests.
Design intention: Guide students to build a knowledge network, and simply feedback and correct what they have learned. (Class record)
(5) Make a counseling plan and arrange preview.
We have learned the particle reference system and coordinates, and we will learn time and displacement together next class. After this lesson, you can preview this part first, focusing on the difference between vector and scalar. How to draw an appropriate conclusion? And complete this section of after-school exercises and after-school expansion assignments.
Design intention: arrange the preview homework for the next class to consolidate and improve this class. After class, the teacher will review the expansion training in this section in time.
Nine, blackboard writing design
I. Objects and particles:
1, what is a particle?
2. Conditions for treating an object as a particle.
3. Particles are ideal physical models.
Second, the reference system:
1, definition.
2. Choose different reference frames to observe the same movement, and the observation results will be different.
3. The frame of reference can be selected arbitrarily, but the principle of selection should make the movement and description as simple as possible.
Third, the coordinate system:
1, the coordinate system is stationary relative to the reference system.
2. Three elements of coordinates: origin, positive direction and scale unit.
3. Coordinate the position of particles.
4. Describe that the position of the particle changes with the change of coordinates.
X. Teaching reflection
In this lesson, through the analysis of familiar examples, students can naturally understand that "in some cases, the size and shape of an object can really be ignored" and "the mass of an object can be highlighted and simplified as a point with mass". This fully explains the condition of simplifying an object into a particle and two basic properties of the particle.
In order to emphasize the concept of coordinates, textbooks use symbols commonly used in mathematics and physics, that is, in linear motion, x represents the position of a particle, and in polar coordinates, △ X = x 1-x2 represents the displacement of a particle. When expressing the change of physical quantity, "△" is actually the symbol we used before, and students will not find it difficult. On the contrary, it is easier for students to distinguish a physical quantity from its change, because the symbol clearly shows the change of the physical quantity.
It is the characteristic of this book to clearly distinguish a physical quantity from the change of this physical quantity. It is often necessary to distinguish these two physical quantities in physics, and consciously emphasizing their differences will be beneficial to future study. In the next section, the relationship between time and time interval is the same.