Teaching plan design of physical curve movement in senior high school
Learning objective 1. Know what curvilinear motion is and the direction of velocity in curvilinear motion.
2. Understand that curvilinear motion is variable-speed motion.
3. It is necessary to understand that the condition for an object to move in a curve is that the direction of the external force is not in a straight line with its speed direction.
Learn the speed direction in key curve motion and the conditions for objects to do curve motion. Difficulties in learning: Understand and master the conditions for an object to move in a curve. Learning methods: experiment, explanation, induction, reasoning, collective lesson preparation, individual lesson preparation, first class and topic introduction.
So far, we have only studied the motion of objects along a straight line. In fact, in nature and technology, curvilinear motion can be seen everywhere. Objects thrown horizontally move along a curve during landing; The earth revolves around the sun, and its trajectory is close to a circle and also a curve. Throwing objects, the earth is revolving, and their movements are curved. Then, from this lesson, we began to study the law of curve motion.
Goal guidance
1. Know what curve motion is and the speed direction of curve motion.
2. Understand that curvilinear motion is variable-speed motion.
3. It is necessary to understand that the condition for an object to move in a curve is that the direction of the external force is not in a straight line with its speed direction.
Third, self-study.
The content of the first section of chapter 5 in the students' self-study textbook.
Guided query
A, the displacement of curvilinear motion:
1. Selection of coordinate system: Which coordinate system should be selected when studying the curvilinear motion of an object in the same plane?
2. Displacement description: when an object moves to a certain point, its displacement can be expressed by its component vector in the direction as far as possible, and the component vector can be expressed by this point.
Second, the speed of curve motion
1. Velocity direction: the velocity of a particle at a certain point is the direction along the curve at that point.
2. Nature of motion: The speed of a particle moving in a curve is changing, that is, the speed is changing all the time, so the curve motion must be motion.
3 Description of velocity: Component vectors in two mutually perpendicular directions can be called component velocity, where vx= vy=.
Third, examples of action description:
1. Location of wax block: The speed at which the wax block rises along the glass tube at a uniform speed is vy, and the speed at which the glass tube moves to the right at a uniform speed is vy, counting from the moment when the wax block starts to move. Therefore, at time t, the position p of the wax block can be expressed by its two coordinates, x= y=.
2. Velocity of wax block: the magnitude of velocity v=, and the direction of velocity tan=
.
3. The trajectory of wax block movement: y=, which is one.
Four, do the curve movement conditions:
1, from the dynamic point of view: when an object is acted by a reasonable direction and its speed direction, it moves in a curve.
2. From the kinematics point of view: when the acceleration direction of an object is the same as its velocity direction, the object moves in a curve.
Verb (abbreviation of verb) sublimation of goal
First, the understanding of curvilinear motion
1, the speed of curve motion;
2. The nature of curvilinear motion;
3. Five kinds of sports.
Teaching plan design of physical curve movement in senior high school II
First, the design ideas
As far as the knowledge of curve motion is concerned, there are actually only two, one is the speed direction of curve motion and the other is the condition of curve motion. If the teacher directly tells the students the above two conclusions after simple picture display and theoretical deduction, I believe the students can easily accept them, and the rest of the time can be consolidated through practice. However, it is suspected of paying too much attention to physical knowledge and ignoring the core literacy of physical thinking and methods. Therefore, the key to solve this problem lies in the concept and method of teaching.
In this class, under the guidance of a large number of demonstration experiments, teachers let students independently obtain experimental conclusions by observing experimental phenomena, and then directly verify the conclusions drawn by students through experiments, completely following the inquiry method of Galileo's scientific experiments, that is, finding problems-guessing-exploring-verifying-summarizing-communicating, which is actually the concrete application of the problem chain and learning guidance mode proposed by the school to find problems. In the process of problem discovery, students are guided to think and disperse through open experiments; In the process of solving problems, experience the fun of knowledge acquisition through group cooperation and discussion; In the process of problem perception, students independently summarize and use what they have learned to guide their real life, thus realizing the significance of STS and improving their scientific literacy.
Second, teaching material analysis
Teaching requirements: know the concept of curvilinear motion, know the direction of velocity in curvilinear motion and understand that curvilinear motion is a kind of variable-speed motion, know the conditions for objects to do curvilinear motion, and master the relationship between velocity, resultant direction and curvilinear bending.
This lesson is the basis of the whole chapter, but it is not the key content. Through experiments and discussions, students can realize that the speed of an object moving on a curve is changing all the time, the curve motion is variable, and the direction of the speed is the tangent direction of the curve. This lesson mainly talks about two points: 1, what is the speed direction of curve motion; 2. Conditions for the motion of an object along a curve.
Thirdly, the analysis of learning situation.
In the compulsory course 1, students have mastered several kinds of sports, but they are all limited to linear sports, and curve sports are the most common sports. In fact, in junior high school, students have learned what linear motion is and what curved motion is. They know that curved motion is a common motion, but they don't know the characteristics and reasons of curved motion. Although students learn the vector of speed in the compulsory course 1, they often ignore the direction of speed in actual learning, which means it is difficult for students to grasp that "curvilinear motion is variable-speed motion". In addition, the conclusions that "the velocity direction of curvilinear motion is tangent direction" and "the resultant force and velocity are not linear, and the object moves in curvilinear motion" are simple, but the process of experimental verification is not easy. When students experiment in groups, it is easy to roll away small steel balls, which requires students' serious cooperation. Geometric drawing may be difficult at first, and the teacher can give appropriate hints. The main learning behaviors of students are observation, answer and experiment.
Fourth, teaching objectives.
1, knowledge and skills:
(1) Know the speed direction of curvilinear motion and realize that curvilinear motion is variable-speed motion.
(2) Understand the conditions for the object to move in a curve, and master the positional relationship between the bending direction of the trajectory and the stress direction.
(3) Apply the knowledge of curve motion to the practice of production and life.
2. Process and method
(1) Experience the inquiry process of finding problems, guessing, exploring, verifying, summarizing and communicating.
(2) To experience and understand the research problem, we must first go from special to general, and from qualitative to quantitative.
(3) Try to apply the principle of mathematical geometry to the study of physics.
3. Emotional attitudes and values
(1) Take the initiative to observe carefully, pay attention to the science around you, and actively participate in learning activities.
(2) I feel that scientific research problems stem from life practice, and the conclusions I get serve life practice, and I feel that I have applied what I have learned.
Verb (abbreviation of verb) is the key and difficult point.
Key point: let students experience the experimental process of obtaining "the speed direction of curve motion is tangent direction"
Difficulty: How to make students get the conditions for objects to do curvilinear motion?
Six, teaching strategies and means
In teaching activities, students' subjectivity and teachers' guidance and service are reflected.
In the teaching method: starting from the problem, making the problems interlocking, from the discovery of the problem, to the solution of the problem, and finally to the perception of the problem, forming a problem chain to guide learning; Relying on the form of group cooperation, group discussion, cooperative research and common progress.
In the teaching process: basically according to Gagne's information processing model. Attract attention-inform students of learning objectives-stimulate memories of premise learning-present stimulating materials-provide learning AIDS-lead out homework-provide homework-provide feedback-evaluate homework-promote maintenance and migration, and organically integrate teaching, learning, practice and evaluation through question chain.
In the learning process: highlight students' finding problems-guessing-exploration-verification-conclusion-application.
In the cognitive process, it highlights the human learning law and cognitive law, that is, from special to general, from simple to complex.
In philosophy teaching, it is emphasized that scientific research comes from and serves life practice, and it is recognized that "conclusions must be based on science".
Seven, preparation before class
Students don't need to preview textbooks, otherwise, just like guessing activities with known answers, those inquiry activities and questions and answers are meaningless.
Prepare the teaching equipment, the specific teaching equipment are: remote control aircraft model; Darts and darts; Roller coaster track model; Grinding wheel; Film gloves, small steel balls, red inkpad, white paper, arc guardrail (plastic+iron sheet), inclined plane, bar magnet, debugging multimedia equipment.
Eight, the teaching process
curvilinear motion
Teacher: Good morning, class! Starting from today, we will enter the study of Compulsory 2. Please look at these kinds of movements: 1. The movement of the ball along the roller coaster track model; The second is the movement of the wing and fuselage of the helicopter model. (Projection stays at 1 page: title)
Question link
Question 1: Please observe, what are the similarities between these sports?
Health: Everything is moving in a curve.
Teacher: From the trajectory, these movements are very different from the linear movements we learned before. In real life, there are many curved movements (play the projection page 2: pictures of curved movements), so it is necessary for us to do some research on this kind of movements. We call the trajectory curvilinear motion, which is called curvilinear motion. (Play Projection Page 3: Definition of Curve Motion)
Question 2: So what do you think is worth studying about curvilinear motion? (Open-ended questions)
Health: the displacement, speed, acceleration and trajectory of the object, and why the object moves in a curve.
Teacher: Good. The teacher writes down the questions raised by the students on the blackboard one by one, and finally evaluates them one by one. ) What the students just said is really worth studying. We might as well start with the basics. This course mainly solves two problems: one is the speed direction of curve motion, and the other is the condition for objects to do curve motion. The rest, we will learn slowly in the next few classes. (Play the projection page 3: the learning content of this lesson)
Question 3: What do you think are the characteristics of the speed of curvilinear motion? With this question, let's look at several experiments: first, water drops fly out of the rotating feather umbrella; The second is the spark generated by the cutting machine cutting steel. (Please think about it, and the teacher will prompt the students appropriately) (Play projection page 4: umbrella+grinding wheel)
Teacher: How do you observe the movement of raindrops? How does the flying spark move?
Health: Raindrops fly from the umbrella and sparks splash from the grinding wheel.
Teacher: What does this mean?
Health: They all come out from the tangent direction. Along the tangent direction of the circumference, along the tangent direction of the trajectory; The velocity direction of an object moving on a curve is the tangent direction of the trajectory.
Teacher: Good, which means that everyone is very careful in observation. Just a few actions have one thing in common, that is, the object is doing circular motion, which is particularly suspicious. Is the speed direction of general curvilinear motion also along the tangent direction? Therefore, we will further verify this view through experiments. (Play the projection page 5: Query Activity (1)) (Go back to the tutorial: Activity Query (1))
Problem solving link
Query activity (1): speed direction of curve motion.
Teaching plan design of physical curve movement in senior high school III
Teaching preparation
1. Teaching objectives
Knowledge and skills
1. Know the speed direction of curvilinear motion and understand that curvilinear motion is variable-speed motion.
2. Know the conditions under which an object moves along a curve.
3. Learn to use graph theory and right triangle knowledge to solve the problem of synthesis and decomposition of displacement and velocity.
Process and method
1. Learn to analyze the curve movement in daily life.
2. Combine Newton's second law to explain the conditions for an object to move in a curve.
3. Through the experiment of red wax block movement, observe and analyze the movement of the research object in the plane rectangular coordinate system.
Emotions, attitudes and values
Curved motion is a common form of object motion. Pay attention to the movement state of different objects around you, think about the reasons for different movements, and experience the fun of analyzing practical problems.
2. Teaching emphases/difficulties
Multimedia and blackboard writing
3. Teaching tools
label
teaching process
First, the displacement of curvilinear motion.
Asking and communicating: The plane doing an air show in the picture is spiraling up. In order to describe the displacement of the plane, can we choose the plane rectangular coordinate system? If not, what coordinate system should I choose?
It is pointed out that the plane does not move in the plane, so its displacement cannot be described in the plane rectangular coordinate system, and it is necessary to establish a three-dimensional coordinate system to describe the displacement of the plane.
1. Basic knowledge
(1) curve motion
The trajectory of particle motion is the motion of curve.
(2) Establish a coordinate system
When studying the displacement of an object moving in a curve in the same plane, the plane rectangular coordinate system should be selected.
Step 3 describe
For an object moving on a curve, its displacement should be expressed as a component vector in the direction of the coordinate axis.
Thinking and judging
(1) The motion of the satellite around the earth is curved. (√)
(2) When studying the movement of kites, you can choose the plane rectangular coordinate system. (×)
(3) When an object moves to a certain point, the vector of displacement can be expressed by the coordinates of that point. (√)
Second, the speed of curve motion
Inquiry communication
When grinding a tool on a grinding wheel, which direction does the spark at the contact between the tool and the grinding wheel fly out? When the umbrella rotates, which direction does the water drop fly out? What conclusions can be drawn from the above two phenomena?
It is suggested that Mars fly out along the tangent direction of the contact between the grinding wheel and the cutter, and raindrops fly out along the tangent direction of the circumference of each point on the umbrella edge. From these two phenomena, it can be seen that when an object moves in a curve, the speed direction of a certain point should be the tangent direction along the trajectory of that point.
1. Basic knowledge
(1) speed direction
The velocity of a particle at a certain point, along the tangent direction of the curve at that point.
(2) the essence of movement
The velocity direction of a particle moving in a curve is always changing, that is, the velocity is always changing, so the curve motion must be variable.
Step 3 describe
It is expressed by two velocity components in the vertical direction, which is called fractional velocity.
Thinking and judging
(1) The velocity of water obliquely emitted by the fountain is tangential. (√)
(2) The speed of curvilinear motion can be constant. (×)
(3) The fractional velocity is scalar. (×)
3. Velocity characteristics of curvilinear motion
The characteristics of curve motion speed: first, the speed changes at all times; Second, the speed direction is always along the tangent direction.
(1) The velocity direction of a particle in curve motion at a certain moment (or a certain position) is the direction in which the particle moves freely after leaving the curve at that moment (or that point), that is, the tangent direction of that point on the curve.
(2) Speed is a vector with both magnitude and direction. If only the speed changes during the movement, and the speed direction of the object remains unchanged, then the object can only move in a straight line. Therefore, if the object moves in a curve, it means that the speed direction of the object has changed.
Three. Examples of sports descriptions
Inquiry and communication: in the description of wax block movement, how does the speed of wax block change if only the speed of glass tube moving to the right is increased?
1. Basic knowledge
(1) wax block position (as shown in Figure 5, 12)
The speed of wax block rising along the glass tube is vy, and the speed of glass tube moving to the right is vx. Time is counted from the moment when the wax block starts to move, so at time t, the position p of the wax block can be expressed by its two coordinates, x=vxt and y=vyt.
(2) Velocity of wax block
Four, the conditions for the object to do curvilinear motion
1. Basic knowledge
(1) When the direction of resultant force on an object is not in a straight line with its velocity direction, the object moves in a curve.
(2) When the directions of acceleration and velocity are not in a straight line, the object moves in a curve.
Thinking and judging
(1) When an object moves in a curve, the resultant force must be a variable force. (×)
(2) When an object moves in a curve, the resultant force must not be zero. (√)
(3) When an object moves in a curve, the acceleration must not be zero. (√)
Inquiry communication
Can you sum up the conditions for an object to move in a straight line?
Five, the nature of the movement and the judgment of the trajectory
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