casino club granville:casino,club,granville,Zhang,Zo:Zhang Zongchang was also used by Yang Qiu as a Japanese ambassador People's Education Edition Eighth Grade Physics Book Case 2nd Section Two Force Balance Data Download People's Education Edition Eighth Grade Physics Book Cases Second Secti

casino club granville

Zhang Zongchang was also used by Yang Qiu as a Japanese ambassador

People's Education Edition Eighth Grade Physics Book Case 2nd Section Two Force Balance Data Download People's Education Edition Eighth Grade Physics Book Cases Second Section Two Force Balance Second Section Two Force Balance 1 New lesson in class [teaching goal] knowledge and skill 1. Know the balance concept of force, know the two equilibrium states - static state and uniform linear motion state.

2. Understand the balance conditions of the two forces. 3. Two-force balance conditions will be applied to analyze and solve simple problems. Process and method 1. Understand the concept of two-force balance by organizing student discussions and analyzing the force of objects; The conditions for the balance of the two forces are obtained through the organization of the inquiry experiment. Emotions, attitudes and values ??1. By exploring the conditions of the balance of the two forces, students are encouraged to establish ideas and methods for solving physical problems by experimental methods. 2. Through inquiry experiments, students will be further trained in the scientific attitude and rigorous scientific style of experimenting with facts. [teaching difficulties] focus 1. Know the conditions of the balance of the two forces. 2. Apply the two-force balance condition to solve the actual problem. Difficulties: Students design experiments to explore the balance of the two forces. [Teaching Preparation] or [Experimental Preparation] Teacher: Multimedia courseware. For students (each group): plastic sheet, cotton thread, hook code, pulley, scissors [teaching process] main teaching process teaching content teacher activities student activities first, create scenarios, introduction (design intent: let students generate cognitive conflicts, stimulate inquiry Desire.) Appreciation video review answer: When all objects are not subjected to force, they always remain at rest or in a uniform linear motion state. Panel discussion: No, and use life's examples to illustrate: static books, tables, cars traveling at a constant speed, etc. are all subject to force. Second, cooperative exploration, construction knowledge (a) balance of power to define equilibrium state 1. [Example Force Analysis] Please analyze the static cup on the table, the goods hoisted by the crane at a constant speed, and the force of the car traveling at a constant speed. Note: In real life, objects are often subjected to multiple forces at the same time and are in a state of static or uniform linear motion. The motion state is the same, and the effects of these forces cancel each other out. 2. [Guiding Summary]-----Cognitive Concept 1. When an object is subjected to several forces, if it is still or at a constant linear motion, we say that these forces are balanced. 2. The state of stationary or uniform linear motion is called 'balanced state'. 3. [Feedback practice] The balance of the following objects is () A, roller coaster B turning on a circular orbit, rocket C speeding up, train D entering the station, and a car traveling at a constant speed on the road [think about it] 1. What is the sign of the object being balanced? 2. What happens to an object that is unbalanced? (Design Intent: Analyze the cognitive concept of the stress of common objects, easy to understand and accept, and raise awareness through practice and problem discussion.) Stress analysis: the cup is supported by gravity and table, the gravity of the cargo and the tension of the steel rope In addition to the support of gravity and the ground, the car is also subject to traction and drag. Cognition is what is the balance of power and what is the state of balance. Learn to use: Determine whether the motion state of the object is in equilibrium (stationary or uniform linear motion). The direction of uniform circular motion changes, not the balance force. Thinking answer: The object is in a static or uniform linear motion state; its motion state will change when it is unbalanced. (2) Balance of two forces 1. Definition 2. Exploring the conditions of the two-force balance [leading cognition] Like the teacup, the cargo, and the object in the previous example, under the action of two forces, it can stand still or do a uniform linear motion. We call these two forces a two-force balance. The balance of the two forces is the simplest scenario in the balance of forces. [Experimental exploration, collaborative research] 1. Ask the question: If there are only two forces acting on the object and the object is in equilibrium, what conditions should the two forces satisfy? 2. Conjecture hypothesis: Cognitive power, we must start with the three elements of force, and ask the students to combine the force analysis of the object that has been balanced, and proceed from the three elements of force to make bold conjectures. 3. Design experiment: [Introduction of experimental equipment] Hook code, thin line, plastic sheet What method do you intend to explore? Note: The experimental object is a plastic sheet. In order to ignore the influence of gravity, the plastic sheet should be light. After the discussion between teachers and students, the program was summarized. 4. Carry out the experiment: [Friendly Tips] In the following experiments, observe and record whether the plastic sheet will be balanced, whether the motion state changes, what is the relationship between the two tensions, under what conditions will maintain the balance state (keep the motion state not Change), what is explained.

[Experiment 1] Hanging hook code on both sides; [Experiment 2] Hanging heavy hook code.

[Experiment 3] (1) Hang the hook code on both sides, move the card down so that the direction of the two forces is not reversed, and release; (2) When the plastic sheet is stationary, observe the direction of the two forces.

[Experiment 4] (1) Hang the hook code on both sides, rotate the plastic piece at a certain angle, so that the two forces are not on the same straight line and release; (2) When the plastic piece is stationary, observe the two forces.

Record the phenomenon in the table: [Experiment 5] Please use scissors to cut the plastic piece from the middle and observe whether its movement state changes. What can you explain? (Design Intent: To train students to design experiments according to problems, so that students can develop observation ability, hands-on ability, cooperation spirit in the experiment, and initially develop a scientific and realistic attitude in learning.

) 5. Analytical argument: [inductive summary] ----- Condition 2 of the two-force balance acts on the same object, 2 forces are equal in size, 3 directions are opposite, 4 and in a straight line.

[Acknowledgment]: Same body, equal big, reverse, collinear.

[Feedback Exercise] 1. F1 and F2 are balanced forces are () 2. The book that rests on the horizontal table, the balance is () A. The gravity of the book and the pressure of the book against the table B. The pressure of the book against the table and the gravity of the table C. The gravity of the book and the support of the table to the book D The book's pressure on the table and the support of the table to the book recognize what is the balance of the two forces.

Consider the conditions of the two-force balance: 1. Equal size 2. Reverse direction 3. Communicate on the same line: Control variable method.

The group exchanges collaborative design experiments and demonstrates communication.

The group collaborates on the experiment, observes the experiment, and records the phenomenon in the table: the hook code is not equal, the plastic piece can not be balanced, the movement state changes, the two pulling forces are not equal; the heavy hook code, plastic piece Can not maintain balance, the state of motion changes, the two pull forces are equal.

Communication Summary: When the two forces are balanced, the two forces must be equal in size.

The plastic sheet cannot be balanced and the movement state changes.

Communication Summary: To balance the two forces, the two forces must be in the opposite direction.

The plastic sheet cannot be balanced and the movement state changes.

Communication Summary: To balance the two forces, the two forces act on the same line.

The movement state of the plastic sheet changes, and the communication summary: When studying the balance of the two forces, the two forces must act on the same object.

Students combine experimental phenomena and experimental forms to analyze and demonstrate, summarize and answer.

Learning to use: Use the conditions of two-force balance to solve problems.

This question is also a student's easy question.

First judge whether the two force-bearing objects are the same object, and then use other conditions to judge.

(3) Two-force balance application [solving problems, cooperation seminars] 1. According to the state of the object, the force is analyzed. [Analysis of the paradigm] The skydiver descends in a straight line at a constant speed. If the total gravity of the person and the umbrella is known to be 1000N, can you tell the magnitude and direction of the resistance of the person and the umbrella? Dial: Clear the research object → Analyze the motion state → Perform the force analysis → Solve the problem according to the two-force balance condition.

[Tracking practice, breaking through the wrong points] If a classmate does not push a desk with the horizontal thrust of F=10N, how much resistance does the desk receive? Breaking through the error-prone points: By using the two-force balance analysis solution, the wrong view that the thrust is less than the resistance is eliminated.

2. Analyze the state of motion according to the force of the object [Typical analysis] When the car travels in a straight line, the traction force is F, and the resistance is f.

(1) What kind of exercise does the car do when F>f? (2) What kind of exercise does the car do when F=f? (3) What kind of exercise does the car do when F

Solution: The desk is still → subject to balance → f=F=10N. Discussion: (1) Unbalanced, the car makes accelerated linear motion; (2) Two-force balance, the car makes uniform linear motion; (3) Unbalanced, the car does slow down linear motion.

(4) Expanding the extension 1. Comparison of balance and interaction forces 2. Summarize the relationship between exercise and force [比比比] What are the similarities and differences between balance and interaction? [Summary] The same point: Both are equal in size, opposite in direction, on the same line; different points: the force of the balance force is the same object, and the interaction force is two objects.

[Think about the discussion] Ask the students to combine the Newton's first law and the balance of the two forces to think about the relationship between power and exercise. [Summary] 1. Force is the reason for changing the motion state of the object; 2. The motion of the object does not need force to maintain; 3. The object is stationary or uniform - no force or balance 4, the object is balanced - ---Still or uniform line 5, the object is subject to non-equilibrium force----the state of motion changes 6. The state of motion changes, it must exert force on the object, and it is unbalanced force; 7. Strong force on the object, movement The status does not necessarily change.

[Feedback Exercise] Use a thin wire to slap an eraser and make a uniform circular motion on the horizontal surface. The rubber is in motion () A. The rubber is affected by the balance force. B. The movement state of the rubber does not change. The direction of movement of the rubber is constantly changing, and it is subject to the unbalanced force. D. The rubber maintains a uniform circular motion because it has an inertial communication discussion: the comparison of the two-force balance and the interaction force in the three elements of force.

(Design Intent: Deepen understanding of both.

Avoid confusion.

) Exchange discussion and answer.

(Design Intent: Improve understanding of the relationship between exercise and force.

) Answer: The direction of motion of the circular motion changes, the state of motion changes, and it must exert force on the object, and it is an unbalanced force. Answer: C. Lesson summary: Review the learning content of this lesson. What are your gains in class? What other doubts students are discussing to sort out knowledge, exchange gains and doubts.

Fourth, classroom inspection teacher inspection, lecture evaluation to complete the test questions, answer to see Annex 1 5, layout assignments to present thinking questions, see Annex 2 after the completion of the [board design] the second quarter of the two balance of power, force Balance: 1. When the object is subjected to several forces, if the effects of several forces cancel each other out, so that the object is in a static or uniform linear motion state, we say that these forces are balanced.

2. The state of stationary or uniform linear motion is called “balanced state”.

Second, exploration: The two forces acting on the same object, if they are equal in size, opposite in direction, and on the same line, the two forces are balanced with each other.

Application of the balance of three and two forces 1. The object is in equilibrium → subject to balance 2, the object is balanced → in equilibrium [teaching reflection] First, the 'bright spot' of the teaching plan 1. The improvement of the experiment is innovative. Using light paper instead of the car to slide on the board, the improved experiment reduces the impact of friction on the experimental phenomenon, not only can directly study the relationship between the two forces, but also hang the demonstration board on the blackboard, increase the experiment Intuitive and visual.

2. Linking links, teaching design is conducive to students participating in the whole process of knowledge formation, realizing the self-construction of knowledge, a car with a weight of ×104N, when it is on the horizontal road at a speed of 60m/h. The traction force received at a constant speed is 2000N, then the resistance of the car is that the car is stationary on the horizontal ground. 3. The electric light hanging on the ceiling with wires, the force received at rest is a pair of balance forces () A. The tension of the ceiling to the wire and the tension of the wire to the ceiling. The pulling force of the electric lamp on the electric wire and the pulling force of the electric wire on the electric lamp C. The tension of the wire against the lamp and the gravity received by the lamp D. The pulling force of the electric light on the electric wire and the gravity received by the electric lamp 4, as shown in the right figure, push the large wooden box resting on the horizontal ground with the horizontal force without pushing.

At this time, the wooden box is subjected to ()A. The thrust is less than the friction force B. The thrust and friction must be equal in size C. The thrust must be less than the gravity D. The direction of thrust and friction is the same. 5. Figure A is the experimental scenario when Xiaohua explores the balance condition of the two forces. (1) Xiaohua will tie the small card (the negligible gravity). The two pairs of lines cross the left and right brackets respectively. The pulleys are hooked on both ends of the line to make the two pulling directions acting on the small card, and the tension is changed by adjusting (2) When the small card is balanced, Xiaohua turns the small card through an angle. After the loose hand card (optional 'can or' can not be balanced.

The purpose of designing this experimental step is to explore.

(3) In order to verify that only two forces acting on the same object can be balanced, in the case shown in Figure A, Xiaohua's next operation is: (4) When exploring the same problem, Xiaoming will block the wood. Put it on the horizontal table and count the experiment shown in Figure B. The students think that the main reason for Xiaohua’s experiment Xiao Ming’s experiment is A. Reduce the impact of friction on experimental results B. Small cards are easier to get C. It is easy to keep the card balanced in the horizontal direction. The small card is easy to twist. 1. As shown in the figure, when there is no wind, the small ant standing on the ground proudly holds the fruit. For the still fruit, the following statement is correct () A. The fruit is subjected to gravity and the support of the ants, which is a pair of balance forces. The fruit is subjected to gravity and the support of the ants, which is a pair of interaction forces C. The ant's support for the fruit is less than the weight of the fruit. Ants support the fruit more than the weight of the fruit.


Copyright Notice:Original article of this site, in2018/07/26 casino club granville,由 Publish。

Please indicate:casino club granville:http://en.hengzhongyuanlin.com/View/casino_club_granville/

casino club granville Zhang Zongchang was also used Yang

More