Physics as a science that studies the laws of our Universe uses standard research methods and a certain system of units of measurement. It is customary to denote N (newton). What is force, how to find and measure it? Let's study 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 precise mathematical sciences. He 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 little theory
A physical quantity was named in honor of the scientist. Newton is a unit of 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.”
The magnitude of force is measured in newtons for a reason. It was these scientists who created three unshakable “power” laws that are still relevant today. Let's study them with examples.
First Law
To fully understand the questions: “What is a newton?”, “A unit of measurement for what?” and “What is its physical meaning?”, it is worth carefully studying the three main
The first says that if the body is not affected by other bodies, 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. Having designated all the forces acting on it, we find that this is the force of gravity, which is directed vertically downwards, and (in this case of 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. When formulating this law, Isaac Newton was the first to use a 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/s2. This expression is usually denoted in newtons.
What is 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 lower than the speed of light. At speeds close to the speed of light, slightly different laws work, adapted by a special section of physics on 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 certain force, then the second body, in turn, also exerts an effect on the first with a force equal in magnitude.
The very formulation 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 figure out what Newton is. In physics, it is customary to consider everything based on specific phenomena, so we will give several examples describing the laws of mechanics.
- Waterfowl such as ducks, fish or frogs move in or through water precisely by interacting with it. Newton's third law states that when one body acts on another, a reaction always arises, equal 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 action of the water.
- Squirrel wheel - shining example 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 rats can run around. The interaction of two bodies, a wheel and an animal, leads to the fact that both of these bodies move. Moreover, when the squirrel runs fast, the wheel spins at high speed, and when it slows down, the wheel begins to spin more slowly. This once again proves that action and reaction 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. This may seem strange, but in fact, when we walk, we only exert effort to push the ground or any other surface. And we move forward because the earth pushes us back.
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.” What is its physical meaning? So, based on Newton’s second law, this is a derived quantity, which is defined as a force capable of changing the speed of a body weighing 1 kg by 1 m/s in just 1 second. It turns out that Newton is i.e. it has its own direction. When we apply 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 = 1 kg*m/s2. When solving various problems in mechanics, it is often necessary to convert newtons into other quantities. For convenience, when finding certain values, it is recommended to remember the basic identities that connect newtons with other units:
- 1 N = 10 5 dyne (dyne is a unit of measurement in the GHS system);
- 1 N = 0.1 kgf (kilogram-force is a unit of force in the MKGSS system);
- 1 N = 10 -3 walls (unit of measurement in the MTS system, 1 wall equal to force, which imparts an acceleration of 1 m/s 2 to any body weighing 1 ton).
Law of Gravity
One of the most important discoveries scientist, which turned the idea of our planet upside down, is Newton’s law of gravity (read below for what gravity is). 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 capable of attracting 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 also all bodies are magnetized to each other. He derived the law of gravity, which states that any bodies, including celestial bodies, are attracted with force, equal to the product 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 a holistic mathematical model, which is still used in research not only on the surface of the Earth, but also far beyond the borders of our planet.
Unit Conversion
When solving problems, you should remember about the standard ones that are also used for “Newtonian” units of measurement. For example, in problems about space objects, where the masses of bodies are large, very often there is a need to simplify large values to smaller ones. If the solution yields 5000 N, then it will be more convenient to write the answer in the form of 5 kN (kiloNewton). There are two types of such units: multiples and submultiples. Here are the most used ones: 10 2 N = 1 hectoNewton (gN); 10 3 N = 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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