"The woman is created for a man, not a man for a woman" - such a postulate ...
1. With what condition the body speed remains unchanged?
a) if the body rests
b) if the body moves straight and evenly,
c) if the body moves equally,
No. 2. Can the body move both in the presence and in the absence of external influence?
a) yes b) no c) I do not know
№ 3. Dynamics - this is a science studying
a) force that is the cause of movement
b) movement laws
c) the nature of movement
№ 4. Material point -
a) the body, which is considered when solving problems in physics
b) abstract physical conceptused in physics
c) body sizes of which can be neglected
№ 5. The movements of all the bodies surrounding us are subject
A) the laws of mechanics; B) the laws of the dynamics; C) the laws of kinematics.
№ 6. Formulate the Law of Inertia (I Law of Newton)?
Option number 2.
1. Inertial reference system - reference system
2. The reference system includes
A) the reference body; B) body speed;
C) the device counting time; C) length (coordinate);
E) coordinate system; E) the path traveled by the body.
3. The reason for the acceleration is
A) directed physical impact;
B) speed;
C) force.
4. The table lies the book, its acceleration is zero. What forces act on the book.
A) the power of gravity;
B) thread tension force;
C) the power of the centripetal acceleration;
C) the power of the support reaction.
5. Is there a fundamental difference between the land-related reference system, from the reference system associated with the aircraft?
A) yes; B) no; B) I do not know.
6. Which scientists did the study of the relativity of the movement?
Option 3.
1. Are there any traffic?
A) yes; B) no; B) I do not know.
2. The ball begins to move after the football player impact, since
A) the footballer informed the ball of concrete
Acceleration;
B) the footballer handed the ball speed when hit;
C) the footballer made an impact on the body with a certain force.
3. Neinercial reference system - reference system
A) in which the body rests either moving straight and evenly;
C) moving with acceleration relative to other reference systems;
C) in which the body has a certain speed.
4. When does a person go on the ground whether the earth itself affects his legs?
A) yes;
B) no;
B) I do not know.
5. Can I consider the land inertial reference system?
A) yes; B) no; C) I do not know.
6. To define the concept of "material point" in physics.
Option number 4.
1. Body that does not interact with other bodies
A) is always moving at a constant speed;
B) is alone;
C) moves with some acceleration.
2. With a sharp braking of the bus, passengers fall forward in the passage. This happens because the passengers acts
A) the power of inertia;
B) the power of braking of the bus;
C) Resistance strength change in the passenger movement.
3. Does the movement of bodies depend on the size and shape?
A) yes; B) no; C) I do not know.
4. Are material dots in nature exist?
A) yes; B) no; C) I do not know.
5. The main position of the mechanics is the statement:
A) the more body weight, the great power need to be attached to change its speed;
B) the movement cannot occur without the impact of speed;
C) Acceleration is always caused by force.
6. Create at least three examples when the body can be taken for the material point.
Test.
Grade 10
The main statement of mechanics.
Material point.
The first law of Newton.
Page 1.
The main provisions of Newton mechanics are formulated as applied to the simplest material image - to the so-called material point.
The assumption that for some forces cannot be indicated by the body, from which this force acts, does not affect the basic law of movement and the fundamentals of Newton's mechanics, but only makes it abandon some of some significant, but not the main provisions of Newton's mechanics. Since we do not have a different choice, the need forces us, using not Coper-Nickname, and non-inertial reference systems, recognize the existence of forces for which we cannot specify specific bodies, from which these forces act. Although in all other remaining these forces do not differ from those conventional forces with which we are dealing with Newton's mechanics, but still the specified difference of these new forces from ordinary so significant, which seems appropriate to allocate them into a special class of forces.
The main position of Newton's mechanics is that the acceleration of the bodies is due to the forces. In the coordinate systems moving accelerated, additional forces appear due to the presence of acceleration relative to some inertial system. Such forces are called inertia. They are characteristic common feature It is the proportion to the mass of the body to which they act. In this sense, they are similar to the forces of grave.
Thus, experience shows that any acceleration of this class is the result of the action of other bodies. This statement is one of the main provisions of Newton's mechanics.
This result coincides with the former formula (55.2), but when it is derived, only the empirical laws of the Kepler were used here without attracting any additional considerations. This should be expected, because in accordance with the main provisions of Newton's mechanics, the acceleration of the planet should be determined only mutual location Sun and planets and cannot depend on the type of path and the speed of the planet. For the same reason, formula (56.6) can also serve for calculating the accelerations of comet, although the third of the Kepler law for them does not make sense.
As shown (§ 30), the main provisions of Newton's mechanics, and, it means, all the resulting effects can be valid only for coordinate systems moving relative to each other straight and evenly. Then the experiments (in particular, the experience of Foucault) showed that the main provisions of Newton's mechanics are valid in our fixed coordinate system. It means that the fixed coordinate system together with all coordinate systems that do not have acceleration in relation to it forms the class of iner-social coordinate systems in which the main provisions of Newton's mechanics are fair.
The fixed coordinate system and the coordinate system associated with the Earth have an acceleration of one relative to the other. This acceleration is due to the daily rotation of the Earth regarding the Sun and Stars, as well as the annual movement of the Earth. Therefore, the basic provisions of Newton's mechanics that we molded us cannot relate to the fixed coordinate system, and the system of coordinates associated with the Earth. They are true either in that or in another coordinate system. But the experiments that we have still produced were so rude that they did not allow the opportunity to establish in which of the two coordinate systems is the assertion that acceleration is uniquely determined by the configuration. Therefore, with further refinement of experiments, it may be that our statement is unfair for any of these coordinate systems. Special accurate experiments must indicate the coordinate system in which the approval is true that all accelerations are due to the action of any bodies and are uniquely determined by the configuration of these bodies.
Newton laws of movement and consequences that follow them. Considering the same movements in noniner-social reference systems, we are not entitled to directly use the laws of mechanics as they were installed for the cerpete-sized reference system. The transition to new (non-intersocial) reference systems will require how it will be shown in § 78, making significant changes to some of Newton's main provisions.
As shown (§ 30), the main provisions of Newton's mechanics, and, it means, all the resulting effects can be valid only for coordinate systems moving relative to each other straight and evenly. Then the experiments (in particular, the experience of Foucault) showed that the main provisions of Newton's mechanics are valid in our fixed coordinate system. It means that the fixed coordinate system together with all coordinate systems that do not have acceleration in relation to it forms the class of iner-social coordinate systems in which the main provisions of Newton's mechanics are fair.
However, it is almost often convenient to use coordinate systems that have acceleration towards the Sun and Stars. In such non-inertial systems, the coordinates of Newton's mechanics is no longer valid. Classic example This case is the coordinate system associated with the Earth. In order to determine the acceleration of the bodies in relation to the Earth, it is impossible to use the main positions of Newton's mechanics as they have been formulated above. Meanwhile, we often wonder the movements of bodies in relation to Earth. Therefore, the question arises: whether it is impossible to change and supplement the mechanics of Newton so that it can be applied to the coordinate system associated with the Earth. In general, what and how to change in Newton's mechanics so that it can be used in this noninercial coordinate system.
Pages: 1.
"Newton's laws" - the force F is the cause and determines the acceleration a. Vector acceleration is coated with power vector. Features of the 3 Newton Law. Forces are not balanced, because attached to K. different bodies. Shavrova Tatyana Gennadyevna Teacher Physics MOU "May Day Secondary School No. 2". Forces only appear in pairs.
"Newton and laws" - therefore the calculations are so difficult that they have to attract computing machines. Bodies interact. Three Newton's Law describe the movement of everything that surrounds us: from gas molecules to the planets. And now Newton was the laws of Newton in principle to solve any problem of mechanics. The action of one body to another is not unilateral.
"The Three Law of Newton" is the law of Newton. Three Newton Law. Find a picture to your law and explain your choice. Features ??? Newton's law: consolidation of the studied. ??? Newton's law. ?? Newton's law. Newton entered the story as brilliant mathematician and physicist. Check homework. Each group in turn answers questions.
"Newton's strength and laws" is the first law of Newton. Forces only in pairs. If it is equal to zero, then the acceleration is also zero. Vector acceleration is coated with speed vector. Figures and formulas of the Second Law. Dynamics of material point. Only the strength of the same nature. Power is the reason that determines the acceleration. Always when interacting.
"The Law of Newton Physics" - that in physics understand under material point? Word the first Newton law. What are the features of the forces about which in the third law of Newton? What is the main statement of mechanics? Analysis (build a mathematical model of the phenomenon): Select the reference system. Create examples. What is the principle of relativity in mechanics?
"Newton's laws grade 9" - Newton's telescope. The experience of I.Nyuton. Newton's opening - entered the history of physics. Isaac Newton when working .. Isaac Newton's tombstone. Portrait of Newton Isaac, drawn by an unknown English artist. Works belong to mechanics, optics, astronomy, mathematics. These balls helped Isaac in experiments.
Mechanics - a rather complicated science. But its main statement can be submitted in one phrase (see p. 150).
The laws of mechanics are subordinate to the movements of all the bodies around us.
In order to open these laws, Newton did not need any complex devices. Simple experiences were sufficient. The main difficulty was that in the huge variety of movements of the bodies to see it essential, then general, which determines the movement of each body.
The laws of mechanics, as well as all the basic laws of physics, have an accurate quantitative form. But at first we will try to understand these laws qualitatively. So it will be easier to catch the main content of Newton's mechanics. After that, we turn to the quantitative wording of the laws of mechanics.
Selecting a reference system
We already know that any movement should be considered in relation to a specific reference system.
In kinematics, i.e., when describing the movement without considering the reasons for its change, all reference systems are equal. The choice of a certain reference system to solve a problem is dictated by considerations of expediency and convenience. So, when docking spacecraft It is convenient to raise the movement of one of them relative to the other, and not relative to the Earth.
In the main section of mechanics - dynamics - the mutual actions of bodies are considered, which are the cause of changes in the movement of bodies, i.e. their speeds.
It can be said that if kinematics answers the question: "How does the body move?" The dynamics finds out why it is.
The question of choosing a reference system in the dynamics is not easy. We first choose the natural reference system at first glance - the system associated with ground ball. Tel movement near the surface of the Earth will be considered regarding the land itself.
What causes acceleration tel?
If the body lying on the ground, on the floor or on the table, starts moving, then always in the neighborhood you can detect an object that pushes this body pulls or acts on it at a distance (for example, a magnet on an iron ball). The stone raised above the ground does not stay in the air, but falls. It should be thought that it is the action of the Earth leads to this.
The whole set of similar experienced facts suggests that the change in body velocity (i.e. acceleration) always causes the effect on this body any other bodies. This phrase contains the most important statement of Newton's mechanics.
It may turn out that the body rests or moves evenly and straightly, that is, without acceleration (A \u003d 0), although other bodies act on it. But if other bodies do not act on the body, the body speed never changes.
When the book is on the table, then its acceleration is zero, although the action from other bodies is obvious. The book acts the attraction of the earth and the table that does not give her to fall down.
In this case, it is said that actions balance each other. But the book will never come into motion, will not receive
Fig. 2.1
corution, if you do not work on it, a strong jet of air or in any way in any way.
List the experimental evidence that the change in the speed of one body is always caused by other bodies on it, there is no possibility and special necessity. The effect of bodies on each other you can observe every step. But only to observe should be able to.
The footballer hit the ball. I hit - it means that his leg had a certain impact on the ball, and the speed of the ball increased. But what action allows a football player to quickly rush to the target of the enemy? One desire here is small. Be instead of a football field, perfectly smooth ice, and on the legs of a football player instead of Buds with spikes slippers with a smooth sole, it would not be possible. In order to run with acceleration, you need to rest in your feet in the ground. If the legs are sliding, the footballer will not run anywhere. Only friction about the Earth, the effect on the part of the Earth on the football player's feet allow him, and all of us when running and walking to change their speed. Exactly Tych6 "To stay with a run, you need to rest in the ground.
Anyone from his experience knows that it is possible to force any item to change the speed (by numerical value or direction), only having a certain impact on it. It is difficult to suspect students, say, grade 5, chasing the washer, in acquaintance with the laws of Newton's mechanics. But they come correctly. They try, acting as a stick to the washer, so to change the movement of the washer so that it moves in the right direction: to the opponent's goal (Fig. 2.1) or to a teammate partner in a favorable position.
Speed
It should not be thought that the main approval of the mechanics of the co-spermate is obviously and understanding his nothing.
If there is no actions on the part of other bodies on this body, then, according to the basic statement of mechanics, the acceleration of the body is zero, that is, the body will rest or move at a constant speed.
This fact is not at all kind. It took Galilee and Newton's genius to realize it. Newton, after Galileem, it was finally possible to end one of the deepest beliefs of mankind about the laws of traffic law.
Starting from the Great ancient Greek philosopher Aristotle, for almost twenty centuries, everyone was convinced that in order to maintain the constant body velocity, it is necessary that something (or someone) affect him, i.e. the body needs to maintain its movement in the actions produced on the body from the outside , in some active reason; Thought that without such support, the body will definitely stop.
Aristotle considered peace about the land with the natural state of the body that does not require a special reason. After all, the Earth at the time was considered the center of the Universe. Without active reason, the body returns to its natural state of rest.
It seemed to be confirmed in our daily experience. For example, the car with the engine turned off stops on a completely horizontal road. The same can be said about the bike, boat on the water, billiard balls and any other moving bodies. That's why
Galileo Galilee (1564-1642) - the Great Italian Physicist and Astronomer, who first applied the experimental research method in science. Galileo discovered the principle of relativity, introduced the concept of inertia, investigated the laws of the fall of the bodies and movement of the bodies along a clone plane, offered to use the pendulum for measuring time. For the first time in the history of mankind, with the power of the visual pipe, Galilee, opened the mountains on the moon, satellites of Jupiter, Star Station Milky Way, stains in the sun, the phases of Venus. Galilei developed prohibited in those times the church's teachings of Copernicus on the movement of the Earth, for which in 1633 the Roman Catholic Court was convicted. The sentence was canceled by the Vatican 350 years later. Even in our time you can meet people who look at the move just as Aristotle watched. It seems ridiculous motion of the carts with a constant speed, but without a horse!
In reality, the free body, i.e., the body that does not interact with other bodies could maintain its speed constant arbitrarily for a long time or be alone. Only the action from another body can change its speed. Act on the body to maintain its speed constant, you just need because in conventional conditions There is always resistance to movement from the ground, air or water. If it were not for this resistance, then the speed of the car on the horizontal highway and when the engine is turned off, remained constant.
A deeper view of the essence of mechanics
We found out that the body's velocity changes due to the action on him surrounding the bodies. This means that the acceleration of the body in this moment Time is definitely determined by the location of the surrounding bodies and, in the general case, their speeds relative to this body. It is very important to understand that acceleration with a fixed position of the surrounding bodies cannot be any: its value is dictated by the laws of nature and does not depend on what happened with the body in the previous time.
To the velocity of the body this output does not apply. The velocity vector is definitely defined by the impact of the surrounding bodies and at the moment at this point of space can be any depending on what happened to the body in the previous points in time.
The coordinates of the body are also not determined by the effects of other bodies singly. At the moment, at a fixed position of the surrounding bodies, the coordinates of the body can be any depending on how the body moved before it (i.e. the coordinates depend on the initial conditions).
For example, when the stone falls on the ground, its acceleration at each point is determined uniquely attraction to the ground (and the speed relative to the air if the resistance is essential). The speed of the body at this point may be any and depends on how the body was thrown: who threw (strong or weak) when he threw, where methyl, etc. (Fig. 2.2).?
Stone coordinates at the moment time can also be any.
In short, our world is arranged in such a way that the acceleration of bodies is strictly determined by the laws of nature (the laws of Newton's mechanics). The speed and coordinates of the body at the moment depend on what happened with the body before it (from the initial conditions), that is, the laws of nature are not determined.
We will return to this question in §2.9.
Inertial reference system
Until now, the reference system has been associated with Earth, i.e., we considered the movement relative to the Earth. In the light-related system, the acceleration of the body is determined by other bodies on it. Such reference systems are called inertial.
However, in other reference systems, it may be that the body has acceleration even in the case when other bodies do not work.
As an example, consider the reference system associated with the moving bus. With a sharp braking of the bus standing in the passage passengers fall forward, getting acceleration relative to the walls of the bus (Fig. 2.3). However, this acceleration is not caused by any impact on the part of the Earth or the bus directly on passengers. Relative to the land passengers retain their permanent speedBut since the bus slows down its movement, then people lean themselves to his front wall.
Thus, when other bodies do not act on the passenger, it does not receive acceleration in the reference system associated with
Oi XI
Fig. 2.4.
Earth, but relative to the reference system associated with the walls of the bus moving slowly, the passenger has an acceleration ahead.
The same result will turn out if you link the reference system with a moving carousel. Regarding the carousel, all bodies lying on Earth will describe the circle, i.e. will move with acceleration, although no external actions causing this acceleration cannot be detected.
Another example. How will explain the boy rolling on sleds from the mountain that the tree on the top of the mountain and the Mountain itself is removed from it faster and faster, i.e. with acceleration? Nic visible reasons There is no, but the acceleration fact is obvious (Fig. 2.4).
If the body is moving with an acceleration that is not caused by other bodies to it with an acceleration, which is called non-intersocial. So, non-intersocial are the reference systems associated with the bus moving towards the Earth with acceleration, or with a rotating carousel.
In non-aircalable reference systems, the main assertion of mechanics is not performed.
The main statement of mechanics should be tried to understand and remember. Try traceing for his justice, watching the movement of the phone during the day. Why do the speeds of these bodies change?
? Is there a fundamental difference between the land-related reference system, from the reference system associated with the aircraft making a turn?
