LESSON № 2 Grade 9
Topic: Uniform rectilinear motion.
Lesson type: Learning new material
Lesson Objectives:
Introduce students to characteristic features rectilinear uniform motion. Formulate the concept of speed as one of the characteristics of the uniform motion of a body.
Teach students to calculate displacement in uniform rectilinear motion.
LESSON PLAN
Lesson stages
Action
1. Organizing moment
Class readiness for the lesson
2. Repetition of the previous material
Repetition of previous material
3. Studying new material
Learning new material
4.Fixing the material
Fixing the material
5. Homework
Homework
During the classes
Org.moment
(Student greeting)
2. Repetition of previous material and verification homework
At the beginning of the lesson, students are tested on their knowledge of:writing verification work according to the theory of the studied material:
I option
the train moves from Barnaul to Biysk;
passengers are boarding.
the plane is flying;
a person is moving in an elevator;
football player on the field.
What is called material point?
What coordinate system
What's happened trajectory, path, movement?
In what cases is the projection of displacement onto the axis positive, in which is it negative?
What movement is called uniform?
II option
the engine is being repaired;
the vehicle is moving.
tram traffic;
submarine in the ocean;
car racing.
What's happened reporting system?
In what cases can a person's car be considered material point? Explain why.
What coordinate system you choose when solving the following tasks:
What is the difference way from displacement?
Define uniform speed rectilinear motion .
In what cases is the projection of the speed of uniform motion on the axis positive, in which is it negative?
Learning new material
Uniform rectilinear movement called such a movement occurring along a rectilinear trajectory, in which the body (material point) makes the same movements for any equal time intervals.
The movement of a body in rectilinear motion is usually denoteds . If the body moves in a straight line in only one direction, the modulus of its displacement is equal to the distance traveled, i.e.|s|=s . To find the displacement of a bodys for a period of timet , you need to know its displacement in unit time. For this purpose, the concept of speed is introduced.v of this movement.
The speed of uniform rectilinear motion is called a constant vector quantity, equal to the ratio movement of the body to the time interval during which this movement was made:
v=s/t. (one)
The direction of speed in rectilinear motion coincides with the direction of movement.
Since in uniform rectilinear motion for any equal time intervals the body makes equal displacements, the speed of such motion is a constant value (v=const). Modulo
v=s/t. (2)
From formula (2) set the unit of speed.
The SI unit of speed is1 m/s (meter per second); 1 m/s is the speed of such a uniform rectilinear motion at which a material point moves 1 m in 1 s.
Velocity - a vector quantity - has a direction. The direction of speed is the same as the direction of motion. Speed can be constant or variable
Speed units
in SI : [ v ] =
Multiples: 1 km/h = 3.6 m/s; 1 km/s = 1000 m/s
Longitudinal: 1 cm/s = 0.1 m/s; 1 dm/s = 0.1 m/s
Let the axis Oh coordinate system associated with the reference body coincides with the straight line along which the body moves, andx 0 is the coordinate of the starting point of the body motion. Along axisOh directed and movings, and speed v moving body. From formula (1.1) it follows thats=vt . According to this formula, the vectorss And v*t are equal, therefore their projections on the axis are also equalOh :
S
V
s x =v x t. (3)
Now you can establish the kinematic law of uniform rectilinear motion, i.e., find an expression for the coordinates of a moving body at any time. Insofar asx=x 0 +s x , taking into account (3) we have
x=x 0 + v x t. (4)
According to formula (4), knowing the coordinatex 0 starting point of body movement and body speedv(her projection v x per axle Oh ), at any time you can determine the position of the moving body. The right side of formula (4) is algebraic sum, since andX 0 , And v x can be both positive and negative.
Graphical representation of the velocity projection:
V x , m/s
t , c
0
S x =V x *t
V x , m/s
t , c
0
S x =V x *t
V x >0
V x <0
S x >0
S x <0
x, m
Graphical representation of the equation of motion:x=x 0 + v x t
x 0
t, s
x=x 0 -v x t
Fixing the material.
vx, km/h
0
-70
t ,from
Construct graphs of the projection of velocity vectors versus time for two cars moving in a straight line and uniformly, if one moves at a speed of 50 km/h, and the other moves in the opposite direction at a speed of 70 km/h.
Questions on fixing the material:
What is called uniform motion?
How to find the projection of the displacement vector of the body, if the projection of the speed of movement is known?
What sign can the projection of the velocity vector have, and what does this sign depend on?
5. Homework.
Topic: The equation of rectilinear uniform motion.
The purpose of the lesson: to find out what kind of movement is taken as a rectilinear uniform; what is meant by the speed of rectilinear uniform motion; learning to solve problems.
During the classes
I. Checking homework in the form of a frontal survey
1) What is meant by the trajectory of movement?
2) Depending on the shape of the trajectory of movement, there can be ...?
3) How do you graphically represent the trajectory of movement:
The center of the car's wheel relative to the highway?
Points on the tire of the wheel relative to the center of the wheel and relative to the highway when the car is moving?
4) How can you describe the motion of a material point?
5) Write down the equations of motion of a material point in coordinate form.
6) What is the frame of reference?
7) What is called a displacement vector?
8) What is the displacement modulus:
If the direction of the coordinate axis is the same as the direction of the vector?
If the vector is directed at an angle α to the direction of the coordinate axis?
II. Learning new material by the method of heuristic conversation:
1) Describe in detail the movement of the car on the highway. Does it always move uniformly?
3) What is called rectilinear uniform motion?
4) What is called the speed of rectilinear uniform motion?
5) What is the formula for the speed of rectilinear uniform motion? (ʋ=s/t)
6) What is the modulus of speed? (ʋ=∆s/ ∆t)
The equation of motion of a material point for rectilinear uniform motion in vector form is written as follows: r=r 0 +ʋt
In coordinate form, only without a sign - a vector. x \u003d x o +ʋ x t; y= y o +ʋ y t; z=z o +ʋ z t
On the graph, uniform rectilinear motion is depicted as - the area of \u200b\u200ba rectangle which is equal to: s \u003d ʋ x t from this equation follows: x - x o \u003d ʋ x t. This means that the change in the coordinate of the body is numerically equal to the area of the rectangle.
III. Solving problems to consolidate the acquired knowledge
1. The point moves uniformly and rectilinearly in the positive direction of the Ox axis. At the initial moment of time, the point had the coordinate x o = -10m. Find the coordinate of the point in 5s from the beginning of the time reference, if the modulus of its speed is equal to ʋ=2m/s. What is the distance traveled by the point during this time?
IV. Summarize the lesson
V. Reflection
VI. Homework:§ 4, learn the formulas and notation of quantities.
Lesson 2/4
Topic. Rectilinear uniform motion
The purpose of the lesson: to acquaint students with the characteristic features of the rectilinear movement of an evenly accelerated
Lesson type: combined
Lesson plan
Knowledge control |
Independent work "Reference system, trajectory, path and displacement" |
|
Demonstrations |
Rectilinear uniform motion |
|
Learning new material |
1. The speed of rectilinear uniform motion. 2. Displacement in the case of rectilinear uniform motion. 3. Equation for the coordinate in the case of rectilinear uniform motion |
|
Consolidation of the studied material |
1. Problem solving. 2. Security questions |
STUDY NEW MATERIAL
The simplest form of mechanical motion is uniform rectilinear motion. Students are already familiar with this type of movement from the course of physics and mathematics of previous classes.
Ø Rectilinear uniform motion is such a motion when a material point makes the same movements for any equal time intervals.
One of the main kinematic characteristics of movement is speed:
Ø The speed of rectilinear uniform movement is a physical quantity equal to the ratio of movement to the time interval t, during which this movement occurred.
As we can see from the definition, speed is a vector quantity: the direction of speed coincides with the direction of movement. In the case of rectilinear uniform motion, the displacement modulus s coincides with the path l, so in this case we can write that
The unit of speed in SI is 1 m/s.
Ø 1 m / s is equal to the speed of such a rectilinear uniform movement, at which a material point moves a distance of 1 m in 1 s.
Question to the students during the presentation of new material
1. Give examples of rectilinear uniform motion.
2. Shows the speed of the body in the case of rectilinear uniform motion?
3. Is it possible to assert that a body moves uniformly in a straight line if it:
a) every second a distance equal to 1 m passes;
b) moves along a straight line in one direction and covers a distance of 2 m in every second?
4. Which speed is greater: 1 m/s or 3 km/h?
CONFIGURATION OF THE STUDYED MATERIAL
Homework
G1) - 3.10; 3.12; 3.13; 3.16;
р2) - 3.26; 3.27; 3.28, 3.31;
d3) - 3.73, 3.74; 3.76; 3.77.
Lesson Objectives : formulate signs of uniform motion.
During the classes.
I. Organizing time.
II. Checking homework
What is point movement?
What is the reference body?
How can you set the position of a point?
What is a radius vector?
III. Learning new material.
Speed is a vector quantity. It is considered given if its modulus and direction are known. Let's define speed.
In rectilinear motion, the speed does not change in direction. The movement is called uniform rectilinear if the trajectory is a straight line and the point passes equal movements in any equal time intervals.
Experiment
Output: behind
Download:
Preview:
PLAN - SUMMARY OF A PHYSICS LESSON IN GRADE 10
Lesson topic:
"Uniform rectilinear motion".
Lesson Objectives: formulate signs of uniform motion.
During the classes.
- Organizing time.
- Checking homework
What is point movement?
What is the reference body?
How can you set the position of a point?
What is a radius vector?
- Learning new material.
Speed is a vector quantity. It is considered given if its modulus and direction are known. Let's define speed.
The speed of uniform rectilinear motion is a value equal to the ratio of its movement to the time interval during which this movement occurred.
In rectilinear motion, the speed does not change in direction. The movement is called uniform rectilinear if the trajectory is a straight line and the point passes equal movements in any equal time intervals.
Uniform rectilinear motion is a motion in which the body makes equal displacements for any equal intervals of time.
Experiment
Conclusion: for the body makes equal displacements in equal intervals of time.
The displacement during uniform rectilinear motion of the body along the X axis in time t can be calculated:
EQUATION OF UNIFORM RECTILINEAR MOTION IN COORDINATE FORM.
- EQUATION OF UNIFORM RECTILINEAR MOTION IN VECTOR FORM.
V X \u003d (X-X 0 ) / t - SPEED.
- Problem solving
1. The movement of a truck is described by the equation x1=-270+12t, and the movement of a pedestrian along the side of the same highway is described by the equation x2=-1.5t. Make an explanatory drawing (direct the X axis to the right), on which indicate the position of the car and the pedestrian at the initial moment of time. At what speed and in what direction did they move? When and where did they meet?
2. According to the given graphs, find the initial coordinates of the bodies and the projections of the velocities of their movement. Write the equations X(t). According to the schedule, find the time and place of the meeting.
- homework
§7-8, p.22 exercise 1(1)
Lesson type: practical lesson
Lesson format: on-line
Technology: elements of problem-search technology
Expected Result:
be able to apply theoretical knowledge of kinematics in solving experimental problems;
own terminology in Kazakh, Russian and English, in kinematics.
Lesson structure:
Organization of the beginning of the lesson - 2 min
Actualization of basic knowledge - 2min
Awareness and comprehension of educational material - 3 min
Checking homework -3 min
Solving experimental problems - 30 min
Summing up the lesson. -2 minutes
Homework - 1 min
Reflection - 2 min
During the classes:
If I have seen farther than others, it is only because I have stood on the shoulders of giants.
I. Newton
(slide number 3)
I .Organization of the beginning of the lesson ( Psychological mood for the lesson)
Walking along the roads of discovery, we met great scientists, whose life creative feat did not leave us indifferent. But in each of their discoveries there was an invaluable contribution of their predecessors. Once the great English scientist Isaac Newton said: "If I have seen further than others, it is only because I was standing on the shoulders of giants." These words can serve as an epigraph to our lesson.
II .Updating basic knowledge
Block diagram (Types of mechanical movement)
(slide number 4)
III .Awareness and comprehension of educational material.
Repetition of basic concepts and formulas of physical quantities
A) Rectilinear uniform motion
B) Rectilinear uniformly accelerated motion ing
C) Solving a graphic problem
In the last lesson, we considered a graphical method for determining the path traveled by the body over a certain time interval, as one of the optimal methods for solving problems. We use this method to find the average speed for a certain section of the path.
The path traveled by the body in a certain time interval is equal to the area of \u200b\u200bthe figure bounded by the velocity graph.
D) Terminological dictionary
| Kazakh | English | |
| Mechanics | Mechanics | mechanics |
| Kinematics | k kinematics | kinematics |
| mechanical movement | mechanics қozgalys | mechanical movement |
| Material point | materialyk nүkte | material point |
| Coordinate | coordinate | coordinate |
| moving | oryn auystyru | transfer ring |
| Speed | zhyldamdyk | speed |
| Acceleration | Udeu | acceleration |
IV . Checking homework
In the last lesson, the task was to make a device for studying the law of falling bodies, and using the basic property of uniformly accelerated motion to prove that free fall is uniformly accelerated.
Take six identical weights (for example, six identical buttons, screws or nuts) and tie them to an ordinary thread so that the distance between the weights is related to each other as 1:3:5:7:9. If you take the first distance equal, for example, 7 cm, then the second should be 21 cm, the third - 35 cm, the fourth - 49 cm, the fifth - 63 cm.
Hold the appliance by the sixth weight so that the first weight rests on the seat or, better yet, on the bottom of the bucket or basin.
Release the weight and listen for the beats. These strikes must be made at regular intervals, although all loads travel different distances. Why? Prove analytically.
V .Solving experimental problems
Task #1
Investigate the dependence of the speed of uniformly accelerated motion on time
Target: check the statement that the speed of a body moving uniformly accelerated in a straight line changes in direct proportion to the time of motion.
Equipment : tripod, tilt rail, carriage, stopwatch, sensors.
From the definition of acceleration it follows that the speed of the body V, moving in a straight line with constant acceleration, after some time t after the start of movement can be determined from the equation: V = V + at ( one). If the body began to move without an initial velocity, that is, at Vo = 0, this equation becomes simpler: V = at (2). It follows that the body, moving from rest with a constant acceleration but, after time t 1 from the moment the movement starts, will have a speed V 1 = at 1 After some time t 2 his speed will be V 2 = at 2 , After some time t 3 - speed V 3 = at 3 etc. Moreover, it can be argued that V 2 : V 1 = t 2 : t b ; V 3 : V , = t 3 : t 1 etc. (3).
The movement that the carriage will make when moving between the sensors is measured;
The carriage is started and the time of its movement between the sensors is measured;
Repeat the start of the carriage 6-7 times, each time recording the stopwatch readings;
Calculate the average time of movement of the carriage t cf in the area;
The formula determines the speed with which the carriage moved at the end of the first section;
Increase the distance between the sensors by 5 cm and repeat a series of experiments for 2S, and calculate the value of the body velocity at the end of the second section: V 2
Two more series of experiments are carried out, increasing the distance between the sensors by 5 cm in each series. This is how the speed values \u200b\u200bare found V 3 And V 4 .
According to the data obtained, the validity of the relationship is checked: V 2 : V 1 = t 2 : t 1 V 3 : V 1 = t 3 : t 1 E) final result
Task #2
Estimate the reaction time of the experimenter using a wooden school ruler
30 cm long .
The assistant holds the ruler so that it hangs down, and zero division, it is convenient to have it from below. The experimenter holds the thumb and forefinger of the right hand so that the lower end of the ruler is between the fingers and it is easy for him to grab the falling ruler. The assistant suddenly releases the ruler, the experimenter pinches it with his fingers as quickly as he can. The ruler will have time to fly some distance - it can be measured by its own divisions, it is convenient to first hold your fingers opposite the zero division. From this distance, we determine the time of fall, considering the motion of the ruler to be uniformly accelerated. Such movements were studied in the 16th century by Galileo Galilei. He found that these movements are uniformly accelerated, and the acceleration is directed vertically down. His experiment, in which he threw objects down from the Leaning Tower of Pisa and found for the first time that light objects fall down as quickly as heavy ones, was included in the 10 best experiments of the century. Consider Galileo's thought experiment
mental e Galileo Galilei's experiment
Video #4
Summarizing.
Observation and experience are the surest means of understanding nature.
Galileo Galilei
Homework:
