Basic physical quantities, their letter designations in physics. Newton - what is it? Newton is a unit of what? Physical symbols
It's no secret that there are special designations for quantities in any science. Letter designations in physics prove that this science is no exception in terms of identifying quantities using special symbols. There are a lot of basic quantities, as well as their derivatives, each of which has its own symbol. So, letter designations in physics are discussed in detail in this article.
Physics and basic physical quantities
Thanks to Aristotle, the word physics began to be used, since it was he who first used this term, which at that time was considered synonymous with the term philosophy. This is due to the generality of the object of study - the laws of the Universe, more specifically, how it functions. As is known, in XVI-XVII centuries the first scientific revolution, it was thanks to her that physics was singled out as an independent science.
Mikhail Vasilyevich Lomonosov introduced the word physics into the Russian language through the publication of a textbook translated from German - the first textbook on physics in Russia.
So, physics is a branch of natural science devoted to the study of the general laws of nature, as well as matter, its movement and structure. There are not so many basic physical quantities as it might seem at first glance - there are only 7 of them:
- length,
- weight,
- time,
- current,
- temperature,
- amount of substance
- the power of light.
Of course, they have their own letter designations in physics. For example, the symbol m is chosen for mass, and T for temperature. Also, all quantities have their own unit of measurement: the intensity of light is candela (cd), and the unit of measurement for the amount of substance is the mole.
Derived physical quantities
There are much more derivative physical quantities than the main ones. There are 26 of them, and often some of them are attributed to the main ones.
So, area is a derivative of length, volume is also a derivative of length, speed is a derivative of time, length, and acceleration, in turn, characterizes the rate of change in speed. Impulse is expressed in terms of mass and velocity, force is the product of mass and acceleration, mechanical work depends on force and length, and energy is proportional to mass. Power, pressure, density, surface density, linear density, amount of heat, voltage, electrical resistance, magnetic flux, moment of inertia, moment of momentum, moment of force - they all depend on mass. Frequency, angular velocity, angular acceleration are inversely proportional to time, while electric charge is directly dependent on time. Angle and solid angle are derived quantities from length.
What is the symbol for stress in physics? Voltage, which is a scalar quantity, is denoted by the letter U. For speed, the symbol is v, for mechanical work it is A, and for energy it is E. Electric charge It is customary to denote the letter q, and the magnetic flux - Ф.
SI: general information
The International System of Units (SI) is a system physical units, which is based on the International System of Quantities, including the names and designations of physical quantities. It was adopted by the General Conference on Weights and Measures. It is this system that regulates the letter designations in physics, as well as their dimension and units of measurement. Letters are used to represent Latin alphabet, in some cases - Greek. It is also possible to use special characters as a designation.
Conclusion
So, in any scientific discipline There are special notations for different kinds of quantities. Naturally, physics is no exception. There are a lot of letter designations: force, area, mass, acceleration, voltage, etc. They have their own designations. There is a special system called the International System of Units. It is believed that the basic units cannot be mathematically derived from others. Derived quantities are obtained by multiplying and dividing from the basic ones.
Physics as a science that studies the laws of our Universe, uses a standard research methodology and a certain system of units of measurement. it is customary to denote N (newton). What is strength, how to find and measure it? Let's explore this issue in more detail.
Isaac Newton is an outstanding English scientist of the 17th century who made an invaluable contribution to the development of the exact mathematical sciences. It is he who is the forefather of classical physics. He managed to describe the laws that govern even huge celestial bodies, and small grains of sand carried away by the wind. One of his main discoveries is the law of universal gravitation and the three basic laws of mechanics that describe the interaction of bodies in nature. Later, other scientists were able to derive the laws of friction, rest and sliding only thanks to scientific discoveries Isaac Newton.
A bit of theory
A physical quantity was named after the scientist. Newton is a unit of measure for force. The very definition of force can be described as follows: "force is a quantitative measure of the interaction between bodies, or a quantity that characterizes the degree of intensity or tension of bodies."
Force is measured in Newtons for a reason. It was this scientist who created three unshakable "power" laws that are relevant to this day. Let's study them with examples.
First law
For a complete understanding of the questions: "What is a newton?", "The unit of measurement of what?" and "What is it physical meaning?", it is worth carefully studying the three main
The first says that if other bodies do not exert any influence on the body, then it will be at rest. And if the body was in motion, then in the complete absence of any action on it, it will continue its uniform motion in a straight line.
Imagine that a certain book with a certain mass lies on a flat table surface. Denoting all the forces acting on it, we get that this is the force of gravity, which is directed vertically downwards, and (in this case, the table), directed vertically upwards. Since both forces balance each other's actions, the magnitude of the resultant force is zero. According to Newton's first law, this is the reason why the book is at rest.
Second law
It describes the relationship between the force acting on a body and the acceleration it receives due to the applied force. Isaac Newton, when formulating this law, was the first to use the constant value of mass as a measure of the manifestation of inertia and inertia of a body. Inertia is the ability or property of bodies to maintain their original position, that is, to resist external influences.
The second law is often described by the following formula: F = a*m; where F is the resultant of all forces applied to the body, a is the acceleration received by the body, and m is the mass of the body. The force is ultimately expressed in kg * m / s 2. This expression is usually denoted in newtons.
What is a newton in physics, what is the definition of acceleration and how is it related to force? These questions are answered by the formula of the second law of mechanics. It should be understood that this law only works for those bodies that move at speeds much less than the speed of light. At speeds close to the speed of light, slightly different laws work, adapted by a special section of physics about the theory of relativity.
Newton's third law
This is perhaps the most understandable and simple law that describes the interaction of two bodies. He says that all forces arise in pairs, that is, if one body acts on another with a certain force, then the second body, in turn, also acts on the first with an equal force.
The very wording of the law by scientists is as follows: "... the interactions of two bodies on each other are equal to each other, but at the same time they are directed in opposite directions."
Let's see what a newton is. In physics, it is customary to consider everything on specific phenomena, so we will give several examples that describe the laws of mechanics.
- Aquatic animals like ducks, fish or frogs move in or through water precisely by interacting with it. Newton's third law says that when one body acts on another, a counteraction always arises, which is equivalent in strength to the first, but directed in the opposite direction. Based on this, we can conclude that the movement of ducks occurs due to the fact that they push the water back with their paws, and they themselves swim forward due to the response of the water.
- The squirrel wheel is a prime example of the proof of Newton's third law. Everyone probably knows what a squirrel wheel is. This is a fairly simple design, reminiscent of both a wheel and a drum. It is installed in cages so that pets like squirrels or decorative rats can run around. The interaction of two bodies, the wheel and the animal, causes both of these bodies to move. Moreover, when the squirrel runs fast, then the wheel spins at high speed, and when it slows down, the wheel starts spinning more slowly. This once again proves that action and counteraction are always equal to each other, although they are directed in opposite directions.
- Everything that moves on our planet moves only due to the "response action" of the Earth. It may seem strange, but in fact, when walking, we are only exerting effort to push the ground or any other surface. And we move forward, because the earth pushes us in response.
What is a newton: a unit of measurement or a physical quantity?
The very definition of "newton" can be described as follows: "it is a unit of measurement of force." But what is its physical meaning? So, based on Newton's second law, this is a derivative quantity, which is defined as a force capable of changing the speed of a body with a mass of 1 kg by 1 m / s in just 1 second. It turns out that Newton is that is, it has its own direction. When we apply a force to an object, for example, pushing a door, we simultaneously set the direction of movement, which, according to the second law, will be the same as the direction of the force.
If you follow the formula, it turns out that 1 Newton \u003d 1 kg * m / s 2. When solving various problems in mechanics, it is very often necessary to convert newtons to other quantities. For convenience, when finding certain values, it is recommended to remember the basic identities that connect newtons with other units:
- 1 N \u003d 10 5 dyne (dyne is a unit of measurement in the CGS system);
- 1 N \u003d 0.1 kgf (kilogram-force - a unit of force in the MKGSS system);
- 1 N \u003d 10 -3 walls (unit in the MTS system, 1 walls equal to strength, which reports an acceleration of 1 m / s 2 to any body weighing 1 ton).
Law of gravity
One of the most important discoveries of the scientist, which turned the idea of \u200b\u200bour planet, is Newton's law of gravity (what is gravity, read below). Of course, before him there were attempts to unravel the mystery of the Earth's gravity. For example, he was the first to suggest that not only the Earth has an attractive force, but also the bodies themselves are able to attract the Earth.
However, only Newton managed to mathematically prove the relationship between the force of gravity and the law of planetary motion. After many experiments, the scientist realized that in fact, not only the Earth attracts objects to itself, but all bodies are attracted to each other. He deduced the law of gravity, which states that any bodies, including celestial bodies, are attracted with a force equal to the product of G (gravitational constant) and the masses of both bodies m 1 * m 2 divided by R 2 (the square of the distance between the bodies).
All the laws and formulas derived by Newton made it possible to create an integral mathematical model, which is still used in research not only on the surface of the Earth, but also far beyond our planet.
Unit conversion
When solving problems, one should remember about the standard ones that are used, among other things, for "Newtonian" units of measurement. For example, in tasks about space objects, where the masses of the bodies are large, it is very often necessary to simplify large values to smaller ones. If the solution turns out to be 5000 N, then it will be more convenient to write the answer in the form of 5 kN (kiloNewton). Such units are of two types: multiples and submultiples. Here are the most used of them: 10 2 N \u003d 1 hectoNewton (gN); 10 3 N \u003d 1 kiloNewton (kN); 10 6 N = 1 megaNewton (MN) and 10 -2 N = 1 centiNewton (cN); 10 -3 N = 1 milliNewton (mN); 10 -9 N = 1 nanoNewton (nN).
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