This article will talk about how to properly interpret Newton's laws. For the complete concept of the first, second and third laws of Isaac Newton, examples of their application and examples of solving problems will be provided.
Content
Newton made his huge contribution to the basics of classical mechanics thanks to three laws. Back in 1967, he wrote a work called: mathematical principles of natural philosophy. In the manuscript, he described all the knowledge of not only his, but also other scientists. It is Isaac Newton who considered the scientists-physicists to consider the founder of this science. The first, second and third laws of Newton are especially popular, and they will be discussed later.
Newton's Laws: First Law
IMPORTANT: To be able to not only formulate the first, second and third laws of Newton, but also easily implement them in practice. And then you can solve complex problems.
IN the first law It is said about reference systemsthat are called inertial. In these body systems, they move straight, evenly (i.e. at the same speed, in a straight line), in the case when other forces do not affect these bodies or their influence is compensated.
To easily understand the rule, you can rephrase it. More precisely, give such an example: if you take an item on wheels and push it, then the product will go almost endlessly in the case when the friction force, the resistance of the air masses and the road will not be flat. Where such a thing as inertia, It is the ability of the subject not to change speed either in the direction, not in size. Even in physics, the first interpretation of Newton's law is considered inertial.
Before the opening of the rule, Isaac Newton Galileo Galileo also studied inertia and, according to his approval, the law sounded as follows: if there are no strength that acts on the subject, then it either does not move or moves evenly. Newton was able to more specifically explain this principle of the relativity of the body and forces that affect it.
Naturally, there are no systems on Earth in which this rule can act. When some object can be pushed and it will move evenly in a straight line without stopping. In any case, different forces will affect the body, their effects on the subject cannot be compensated. Already one force of gravity of the Earth creates an impact on the movement of any body or object. Also, in addition to her, there is the force of friction, slip, coriolis, etc.
Newton's laws: second law
The open laws of Newton in the last century, in the complex, enable scientists to observe various processes, which occur in the universe thanks to the creation of new technological structures, machines.
To find out what are the causes of movement, you should contact the second law of Newton. It is here that you will find explanations. Thanks to him, you can solve various problems on the topic - mechanics. Also understanding his essence, you can use it in life.
Initially, it was formulated as follows - a change in the impulse (amount of movement) is equal to the power that makes the body move, divided into a variable time. Also, the movement of the subject coincides with the direction of action.
To make it clear, this is as follows:
F \u003d δp/δt
The symbol δ is a difference, is called differential, p is an impulse (or speed), and t is the time.
According to the rules:
- ΔP \u003d m · v
Based on this:
- F \u003d m · ΔV/δp,and the meaning: ΔV/δp \u003d a
Now the formula acquires this view: F \u003d m · a;from this equality you can find
- a \u003d f/m
Newton's second lawit is interpreted as follows:
Acceleration, a moving object is equal to the particular, obtained as a result of division of force into body weight or object. Accordingly, the stronger the power to the object, the greater its acceleration, and if the body weight is greater, then the acceleration of the object is less. This statement is considered the basic law of mechanics.
F - in the formula indicates the amount (geometric) of all strength or extreme.
Estimated power It is the sum of values \u200b\u200b(vector). Moreover, these values \u200b\u200bshould be folded according to the rules of the parallelogram or a triangle. It is ideal for obtaining an answer to know the digital values \u200b\u200bof the forces acting on the object and the size of the angle between the vectors of the forces.
This rule can be used both in inertial and non -inertial systems. It acts for arbitrary objects, material bodies. To make it clearer, if the system is non -inertial, then such forces are used as: centrifugal, the power of the Coriolis, in mathematics, this is written like this:
ma \u003d f + fi,where FI - Inertial power.
How is Newton's law applied?
So an example: imagine that the car was driving off -road and stuck. Another car came to the aid of the driver, and the driver of the second car is trying to stretch the car with the help of the cable. Newton's formula for the first vehicle will look like this:
ma \u003d f Nat. Neti +fty - ft.
Examples of problem solving:
- Through the video they threw the rope. On the one hand, the load hangs on the rope, on the other hand, a climber, and the mass of cargo and a person is identical. What will happen to the rope and the roller when the climber will rise upward. The force of friction of the video, the mass of the rope itself can be neglected.
The solution of the problem
According to Newton's second law, the formula can be mathematically as follows:
- ma1 \u003d fnat.nithi1 - mgma1 \u003d fnat.nithi1 - mg - This is the second law for the climber
- ma2 \u003d fnat. Nity2 - mgma2 \u003d fnat.nith2 - mg - So mathematically you can interpret Newton's law for cargo
- By condition: Fnat. Neti1 \u003d fnat. Nity2
- From here: ma1 \u003d Ma2
If the right and left part of the inequality is divided into M, it turns out that the acceleration and suspended cargo and an rise of a person are equivalent.
Newton's laws: Third Law
Newton's third law has this formulation: the bodies have the ability to interact with each other with the same forces, these forces are directed along one line, but have different directions. In mathematics - this may look as follows:
Fn \u003d - fn1
An example of his action
For a more thorough study, we will consider an example. Imagine an old gun that shoots large cores. So - the core that pushes a formidable weapon will affect it with the same force with which it will pour it out.
Fya \u003d - fp
That's why the gun is rolling back when firing. But the core will fly far, and the gun will move a little in the opposite direction, this is because the guns and the nucleus have different masses. It will also happen when any object falls to the ground. But it is impossible to notice the reactions of the Earth because all falling objects millions of times weigh less than our planet.
Here is another example of the third rule of classical mechanics: consider the attraction of different planets. Around our planet the moon rotates. This occurs by the means of attraction to the ground. But the moon also attracts the earth - according to the third law of Isaac Newton. However, the masses of round planets are different. Therefore, the moon is not able to attract a large planet of the Earth to itself, but it can cause the eji of water in the seas, oceans and tows.
Task
- The insect hit the glass of the machine. What forces arise, and how do they act on the insect and car?
The solution of the problem:
According to Newton's third law, bodies or objects, when exposed to each other, have equal forces in the module, but in the direction of the opposite. Based on this statement, the following solution to this problem is obtained: the insect affects the car with the same force as the car affects it. But the action itself varies somewhat, because the mass and acceleration of the machine and the insect are different.
Video: the first, second and third laws of Newton
