Physics as a science that studies the laws of our universe, uses a standard research methodology and a specific system of units of measurement. The unit of measurement of force is usually denoted by H (Newton). What is power, how to find and measure it? Let's study this question in more detail.
Interesting story
Isaac Newton is an outstanding 17th-century English scientist who made an invaluable contribution to the development of exact mathematical sciences. It is he who is the forefather of classical physics. He managed to describe the laws that obey both huge celestial bodies and small grains of sand, carried away by a stream of wind. One of his main discoveries is the law of gravity 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.
Bit of theory
In honor of the scientist, a physical quantity was named. Newton is a unit of measure for strength. 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 value of force is measured in Newtons for a reason. It was these scientists who created three unshakable "power" laws that are relevant to this day. Let's study them with examples.
First law
To fully understand the questions: "What is a Newton?", "Unit of measurement of what?" and “What is its physical meaning?”, it is worthwhile to carefully study the three basic laws of mechanics.
The first says that if other bodies do not exert any effect 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 movement in a straight line.
Imagine that on a flat surface of a table lies a certain book with a certain mass. Having marked all the forces acting on it, we get that this is the force of gravity, which is directed vertically downward, and the reaction force of the support (in this case, the table), directed vertically upward. Since both forces balance each other’s actions, the resultant force is zero. According to Newton's first law, it is for this reason that the book is at rest.
Second law
It describes the relationship between the force acting on the body and the acceleration it receives as a result of the applied force. When formulating this law, Isaac Newton first used a constant value of mass as a measure of the manifestation of inertia and inertia of the 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 the forces applied to the body, a is the acceleration received by the body, and m is the mass of the body. Strength is ultimately expressed in kg * m / s 2 . This expression is usually designated 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 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 a certain force, then the second body, in turn, also acts on the first with equal modulus of force.
The very wording of the law to scientists is as follows: "... the interactions of two bodies on each other are equal to each other, but at the same time 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.
- Floating animals like ducks, fish or frogs move in or through water precisely because of their interaction with it. Newton’s third law says 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 is due to the fact that they pushes 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 proof of Newton’s third law. What is a squirrel wheel, for sure everyone knows. This is a fairly simple design that resembles both a wheel and a drum. It is placed in cages so that pets like squirrels or decorative rats can run. The interaction of two bodies, the wheel and the animal, leads to the fact that both of these bodies move. Moreover, when the squirrel runs fast, then the wheel spins at high speed, and when it slows down, the wheel begins to spin more slowly. This once again proves that the action and the counteraction are always equal, although they are directed in opposite directions.
- Everything that moves on our planet moves only thanks to the "response action" of the Earth. This may seem strange, but in reality when we walk we make efforts only to push the ground or any other surface. But we move forward, because the earth pushes us in response.
What is a newton: unit of measure or physical quantity?
The very definition of "Newton" can be described as follows: "this is a unit of measurement of force." But what is its physical meaning? So, based on Newton’s second law, this is a derivative that is defined as a force that can change the speed of a body weighing 1 kg in 1 m / s in just 1 second. It turns out that Newton is a vector quantity, i.e., it has its own direction. When we apply force to an object, for example, push a door, we also set the direction of motion, which, according to the second law, will be the same as the direction of force.
If you follow the formula, it turns out that 1 Newton = 1 kg * m / s 2 . When solving various problems in mechanics, it is often required to translate 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 = 10 5 dyne (dyne - unit of measure in the GHS system);
- 1 N = 0.1 kgf (kilogram-force is a unit of force in the ICGSS system);
- 1 = 10 -3 walls (the unit in the MTS system, 1 wall is equal to the force that reports an acceleration of 1 m / s 2 to any body weighing 1 ton).
Law of gravity
One of the scientist’s most important discoveries, which turned the idea of our planet upside down, is Newton’s law of gravity (what gravity is, read below). Of course, before him there were attempts to unravel the mystery of the gravity of the Earth. For example, Johannes Kepler was the first to suggest that not only the Earth has an attractive force, but also the bodies themselves can attract the Earth.
However, only Newton was able to mathematically prove the relationship 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 magnetized 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 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 laws and formulas deduced 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, remember the standard SI prefixes, which are used including for "Newtonian" units of measure. 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 turns out to be 5000 N, then the answer will be more convenient to write in the form of 5 kN (kilo Newton). Similar units are of two types: multiple and fractional. Here are the most used of them: 10 2 = 1 hecto Newton (gN); 10 3 N = 1 kilo Newton (kN); 10 6 N = 1 megaNewton (MN) and 10 -2 N = 1 centiNewton (cN); 10 -3 N = 1 milli Newton (mN); 10 -9 N = 1 nanoNewton (nN).