Presentation "Newton's first law". Presentation on the topic "Newton's laws" Presentation on the topic 1st Newton's law
Inertial reference systems Newton's first law
Compiled by: Klimutina N.Yu.
Teacher of the Municipal Educational Institution "Pervomaiskaya Secondary School" of the Yasnogorsk district of the Tula region
If no forces act on a body, then such a body ALWAYS will be at rest
Aristotle
384 - 322 BC
The body itself can move for as long as desired at a constant speed. The influence of other bodies leads to its change (increase, decrease or direction)
LAW OF INERTIA
If the body is not acted upon by other bodies, the speed of the body does not change
Galileo Galilei
1564 - 1642
Geocentric reference system
from Greek words
“ge” - “earth” “kentron” - “center”
Reference systems in which the law of inertia is satisfied are called INERTIAL
Heliocentric reference frame
from Greek words
"helios" - "sun" "kentron" - "center"
Newton's First Law
Every body continues to be maintained in its state of rest or uniform motion in a straight line until and unless it is compelled by applied forces to change that state
There are such reference systems, called inertial, relative to which a body retains its speed unchanged if other bodies do not act on it or the actions of other bodies are compensated
(historical formulation)
(modern wording)
Isaac Newton
1643 - 1727
GALILEO'S RELATIVITY PRINCIPLE
In all inertial reference systems, all mechanical phenomena occur in the same way at the same
initial conditions
Galileo Galilei
1564 - 1642
FIXING
Lesson summary
Aristotle:
if the body is not acted upon by other bodies, then the body can only be at rest
A reference system is associated with the train. In what cases will it be inertial:
a) the train is at the station;
b) the train leaves the station;
c) the train approaches the station;
d) the train moves uniformly on a straight line
section of the road?
A car with a running engine moves uniformly along a horizontal road.
Doesn't this contradict Newton's first law?
Will a reference frame that moves with acceleration relative to some inertial frame be inertial?
Galileo:
if other bodies do not act on the body, then the body can not only be at rest, but also move rectilinearly and uniformly
Newton:
generalized Galileo's conclusion and formulated the law of inertia (Newton's First Law)
Homework
Everyone: §10, exercise 10
Prepare messages on the following topics:
"Mechanics from Aristotle to Newton"
“The formation of the heliocentric system of the world”
_________________________________________________________
"The Life and Work of Isaac Newton"
Lesson No.
Topic: “Inertial reference systems. Newton's First Law"
Lesson objectives:
Expand the content of Newton's 1st law.
Form the concept of an inertial reference system.
Show the importance of such a section of physics as “Dynamics”.
Lesson objectives:
1. Find out what the dynamics physics section studies,
2. Find out the difference between inertial and non-inertial frames of reference,
Understand the application of Newton's first law in nature and its physical meaning
A presentation is shown during the lesson.
During the classes
Contents of the lesson stage
Student activities
Slide number
Icebreaker "Mirror"
Distribute cards, let the children fill in their names themselves, seat an appraiser
Repetition
What is the main task of mechanics?
Why was the concept of a material point introduced?
What is a reference system? Why is it introduced?
What types of coordinate systems do you know?
Why does a body change its speed?
Uplifting, motivation
1-5
II. New material
Kinematics (Greek “kinematos” – movement) – this is a branch of physics that examines various types of motion of bodies without taking into account the influence of forces acting on these bodies.
Kinematics answers the question:
"How to describe the movement of a body?"
In another section of mechanics - dynamics - the mutual action of bodies on each other is considered, which is the reason for the change in the movement of bodies, i.e. their speeds.
If kinematics answers the question: “how does the body move?”, then the dynamics reveal why exactly?.
Dynamics is based on Newton's three laws.
If a body lying motionless on the ground begins to move, then you can always detect an object that pushes this body, pulls it, or acts on it at a distance (for example, if we bring a magnet to an iron ball).
Students study the diagram
Experiment 1
Let's take any body (a metal ball, a piece of chalk or an eraser) in our hands and unclench our fingers: the ball will fall to the floor.
What body acted on the chalk? (Earth.)
These examples suggest that a change in the speed of a body is always caused by the influence of some other bodies on this body. If the body is not acted upon by other bodies, then the speed of the body never changes, i.e. the body will be at rest or moving at a constant speed.
Students perform an experiment, then analyze the model, draw conclusions, and make notes in their notebooks
A mouse click starts the experiment model
This fact is by no means self-evident. It took the genius of Galileo and Newton to realize it.
Starting with the great ancient Greek philosopher Aristotle, for almost twenty centuries, everyone was convinced: in order to maintain a constant speed of a body, it is necessary for something (or someone) to act on it. Aristotle considered rest relative to the Earth to be a natural state of the body that does not require a special cause.
In reality, a free body, i.e. a body that does not interact with other bodies can maintain its speed constant for as long as desired or be at rest. Only the action of other bodies can change its speed. If there were no friction, then the car would maintain its speed constant with the engine turned off.
The first law of mechanics, or the law of inertia, as it is often called, was established by Galileo. But Newton gave a strict formulation of this law and included it among the fundamental laws of physics. The law of inertia applies to the simplest case of motion - the motion of a body that is not influenced by other bodies. Such bodies are called free bodies.
An example of reference systems in which the law of inertia is not satisfied is considered.
Students take notes in their notebooks
Newton's first law is formulated as follows:
There are such reference systems relative to which bodies retain their speed unchanged if they are not acted upon by other bodies.
Such reference systems are called inertial (IFR).
Cards are distributed into groups and
Consider the following examples:
Characters of the fable “Swan, Crayfish and Pike”
Body floating in liquid
Airplane flying at constant speed
Students draw a poster showing the forces acting on the body.Protection of the poster
In addition, it is impossible to carry out a single experiment that would show in its pure form how a body moves if other bodies do not act on it (Why?). But there is one way out: you need to put the body in conditions under which the influence of external influences can be made less and less, and observe what this leads to.
The phenomenon of maintaining the speed of a body in the absence of the action of other bodies on it is called inertia.
III. Consolidation of what has been learned
Questions for consolidation:
What is the phenomenon of inertia?
What is Newton's First Law?
Under what conditions can a body move rectilinearly and uniformly?
What reference systems are used in mechanics?
Students answer the questions asked
Rowers trying to force the boat to move against the current cannot cope with this, and the boat remains at rest relative to the shore. The action of which bodies is compensated in this case?
An apple lying on the table of a uniformly moving train rolls off when the train brakes sharply. Indicate the reference systems in which Newton's first law: a) is satisfied; b) is violated. (In the reference frame associated with the Earth, Newton's first law is satisfied. In the reference frame associated with the carriages, Newton's first law is not satisfied.)
By what experiment can you determine inside a closed cabin of a ship whether the ship is moving uniformly and in a straight line or is standing still? (None.)
Tasks and exercises for consolidation:
In order to consolidate the material, you can offer a number of high-quality tasks on the topic studied, for example:
1.Can a puck thrown by a hockey player move uniformly along
ice?
2. Name the bodies whose action is compensated in the following cases: a) an iceberg floats in the ocean; b) the stone lies at the bottom of the stream; c) the submarine drifts evenly and rectilinearly in the water column; d) the balloon is held near the ground by ropes.
3. Under what condition will a steamship sailing against the current have a constant speed?
We can also propose a number of slightly more complex problems on the concept of an inertial frame of reference:
1. The reference system is rigidly connected to the elevator. In which of the following cases can the reference system be considered inertial? The elevator: a) falls freely; b) moves uniformly upward; c) moves rapidly upward; d) moves slowly upward; e) moves uniformly downwards.
2. Can a body at the same time in one frame of reference maintain its speed, and change it in another? Give examples to support your answer.
3. Strictly speaking, the reference frame associated with the Earth is not inertial. Is this due to: a) the gravity of the Earth; b) the rotation of the Earth around its axis; c) the movement of the Earth around the Sun?
Now let's test your knowledge that you gained in today's lesson.
Peer check, answers on screen
Students answer the questions asked
Students taking a test
Test in Excel format
(TEST. xls)
Homework
Learn §10, answer the questions in writing at the end of the paragraph;
Do exercise 10;
Those who wish: prepare reports on the topics “Ancient mechanics”, “Mechanics of the Renaissance”, “I. Newton”.
Students make notes in their notebooks.
List of used literature
Butikov E.I., Bykov A.A., Kondratiev A.S. Physics for applicants to universities: Textbook. – 2nd ed., rev. – M.: Nauka, 1982.
Golin G.M., Filonovich S.R. Classics of physical science (from ancient times to the beginning of the 20th century): Reference book. allowance. – M.: Higher School, 1989.
Gromov S.V. Physics 10th grade: Textbook for 10th grade of general education institutions. – 3rd ed., stereotype. – M.: Education 2002
Gursky I.P. Elementary physics with examples of problem solving: Study guide / Ed. Savelyeva I.V. – 3rd ed., revised. – M.: Nauka, 1984.
Feathers A.V. Gutnik E.M. Physics. 9th grade: Textbook for general education institutions. – 9th ed., stereotype. – M.: Bustard, 2005.
Ivanova L.A. Activation of students' cognitive activity when studying physics: A manual for teachers. – M.: Education, 1983.
Kasyanov V.A. Physics. 10th grade: Textbook for general education institutions. – 5th ed., stereotype. – M.: Bustard, 2003.
Kabardi O. F. Orlov V. A. Zilberman A. R. Physics. Problem book 9-11 grades
Kuperstein Yu. S. Physics Basic notes and differentiated problems 10th grade St. Petersburg, BHV 2007
Methods of teaching physics in secondary school: Mechanics; teacher's manual. Ed. E.E. Evenchik. Second edition, revised. – M.: Education, 1986.
Peryshkin A.V. Physics. 7th grade: Textbook for general education institutions. – 4th ed., revised. – M.: Bustard, 2001
Proyanenkova L. A. Stefanova G. P. Krutova I. A. Lesson planning for the textbook Gromova S. V., Rodina N. A. “Physics 7th grade” M.: “Exam”, 2006
Modern physics lesson in high school / V.G. Razumovsky, L.S. Khizhnyakova, A.I. Arkhipova and others; Ed. V.G. Razumovsky, L.S. Khizhnyakova. – M.: Education, 1983.
Fadeeva A.A. Physics. Workbook for grade 7 M. Genzher 1997
Internet resources:
educational electronic publication PHYSICS 7-11 grade practice
Physics 10-11 Preparation for the Unified State Exam 1C education
Library of electronic visual aids - Kosmet
Physics library of visual aids grades 7-11 1C education
And also pictures upon request from http://images.yandex.ru
To use presentation previews, create a Google account and log in to it: https://accounts.google.com
Slide captions:
Basic concepts and laws of dynamics.
a c b v v v Sandpaper Ordinary table Glass Friction resistance
Galileo Galilei (1564-1642 Based on experimental studies of the movement of balls on an inclined plane Based on experimental studies of the movement of balls on an inclined plane The speed of any body changes only as a result of its interaction with other bodies. Inertia is the phenomenon of maintaining the speed of a body in the absence of external influences.
Newton's first law. Law of inertia (Newton's first law, first law of mechanics): every body is at rest or moves uniformly and rectilinearly if other bodies do not act on it. Inertia of bodies is the property of bodies to maintain their state of rest or motion at a constant speed. The inertia of different bodies may be different. (1643-1727)
A reference system is called inertial if it is at rest or moves uniformly and rectilinearly. A reference system moving with acceleration is non-inertial m F F y t The action of one body on another is called a force. F - action of the earth - gravity t y F - action of the thread - elastic force
F t F y Let's eliminate the action of the thread Mentally eliminate the action of the Earth
Now let’s imagine that both actions on the ball are eliminated; logic dictates that it should remain at rest
m F y F t Let us now imagine that this ball is at rest in the carriage, moving uniformly and rectilinearly. At the same time, the same bodies Earth and the thread act on it, and both of these actions are balanced. However, relative to the Earth, the ball is not at rest; it moves uniformly and in a straight line.
Summarizing both of these examples, we can conclude: The body is at rest or moves uniformly and rectilinearly if other bodies do not act on it or their actions are balanced (compensated). From the point of view of modern concepts, Newton's first law is formulated as follows: There are such reference systems relative to which bodies retain their speed unchanged unless other bodies act on them.
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