Physics as a science that studies the laws of our Universe, uses a standard research methodology and a certain system of units of measurement. The unit of force is commonly referred to as N (newton). What is strength, how to find and measure it? Let's explore this issue in more detail.
Interesting from history
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 both 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 the scientific discoveries of Isaac Newton.
A bit of theory
A physical quantity was named after a 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,which 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 its physical meaning?", it is worth carefully studying the three basic laws of mechanics.
The first one 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 absence of any action on it, it will continue its uniform movement 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 the reaction force of the support (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. They call inertiathe 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=am; 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. Force is ultimately expressed in kgm/s2 . 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 directed in opposite directions."
Let's figure out what a newton is. In physics, it is customary to consider everything on specific phenomena, thereforeHere are some examples describing the laws of mechanics.
- Waterfowl 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 proving 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 are moving forward, because the earth is pushing us in response.
What is a newton: a unit of measurement orphysical quantity?
The very definition of "newton" can be described as follows: "it is a unit 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 the newton is a vector quantity, 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=1 kgm/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 H=105 dyne (dyne is a unit of measurement in the CGS system);
- 1 N=0.1 kgf (kilogram-force is a unit of force in the ICSS system);
- 1 N=10 -3 sten any body weighing 1 ton).
The law of universal gravitation
One of the most important discoveries of the scientist, which turned the idea of our planet, is Newton's law of gravity (what is gravity, read below). Of course, before him there were attempts to unravel the mystery of attractionEarth. For example, Johannes Kepler 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 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 derived 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 m1m 2 divided by R2 (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, you should remember about the standard SI prefixes, which are also used for "Newtonian" units of measurement. For example, in problems about space objects, where the masses of 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 ones: 102 N=1 hectoNewton (hN); 103 H=1kiloNewton (kN); 106 N=1 megaNewton (MN) and 10-2 N=1 centiNewton (cN); 10-3 N=1 milliNewton (mN); 10-9 N=1 nanoNewton (nN).
