Isaac Newton: Little biography and description of its laws

Isaac Newton was an astronomer, physical and mathematician, one of the most important scientists in history. Who demonstrated that the natural laws that govern movement on earth and those that govern the movement of celestial bodies are the same. He is the author of a monumental scientific work: Philosophiae Naturalis Principia Mathematica, commonly known as Principia, in which the mathematical foundations of the Universe are explained.

He was interested in Kepler and Galileo’s astronomical studies. He graduated in 1665, demonstrating inclination towards physics and mathematics. At 27 he was already Cambridge professor, he taught and was the author of brilliant theories that would point out the path of modern science.

On the other hand, Isaac Newton is usually considered one of the protagonists of the so -called seven -century scientific revolution, although he was never a friend of publicizing his discoveries (which is why many of them met with many yearsdelay). Newton was a mathematics renovator and formulated the theorem known as the "Newton’s binomial". His first investigations revolved around optics: he explained the composition of white light as a mixture of the colors of the rainbow and designed the first reflector telescope, of the type of those currently used in most astronomical observatories.

And it is that in its definitions Newton distinguishes three types of force indicated as follows:

- The insult force of matter is a power of resistance to all bodies, which has the virtue of persevere to stay in its current state, whether it is at rest or in uniform motion in a straight line.
- The printed force is an action exerted on a body to change its condition, whether at rest or in a straight line during movement.
- The centripetal force is in which the bodies are dragged or impelled, or they even have to go to a point like the center.

Newton formulated the three laws of movement: the first is known as the law of inertia (every body remains at rest or in uniform rectilinear motion if no force acts on it);the second, as a law or principle of dynamics (the acceleration experienced by a body is equal to the force exerted on it divided by its mass);The third law explains that for each force or action exerted on a body there is an equally opposite reaction.

Likewise, the formulation of these laws of movement was preceded by various events, which forged and prepared the thought for the compression and explanation of the behavior of nature.

Therefore, the theoretical basis that allowed Newton to establish its laws is also specified in its Philosophiae Naturalis Mathematica Principia. Thus, the first concept that it manages is that of mass, which is identified as the amount of matter, given the importance of this precision is that it allows to dispense with the qualities that are not physical-mathematics, this when it comes to treating theBodies dynamics.

Therefore, Newton’s laws are described in the following table:

## Law Description

First Law (Law of inertia) "All bodies persevere in their state of rest or uniform movement in a straight line, unless they are forced to change that state by printed forces". Thus, Newton thought about force as an agent of movement change establishing a new equivalence between rest and uniform movement. Since, to accelerate any of these two states, it is necessary to impose a force, but the rest and the uniform movement, persist indefinitely in the absence of forces or if the net force that acts on the body is equal to zero. Likewise, the Net Zero Force corresponds, to the uniform and resting movement, which can be said that it is a balance situation that studies the static. Therefore, in general, the acceleration experienced by a body will depend on the established frame of reference. The reference frameworks where the first law is valid is called the initial frames of reference. Therefore, Newton takes into account that moving bodies are constantly subjected to friction or friction forces, which progressively slows them.

Second Law (Force Law) In this Newton Law, it says that the change of linear momentum is proportional to the printed motor force and occurs according to the straight line along which that force is printed. That is, in this law it gives us foundations to relate the concepts of strength, mass and acceleration, being the basis of study of dynamics. Thus, Newton points out that "the change of movement is proportional to the printed motor force, and is done in the direction of the line in which that force is printed". This means that this second law determines the existing relationship of the net force when it acts on a body is different from zero, which allows the calculation of the acceleration that said body will experience in an inertial reference system. And, the original Newtonian form related the force to the change of the amount of linear movement of the body, if the force is constant the change of the amount of movement will also be constant. Therefore, the change in the amount of movement generated will always be proportional to the external net force. The amount of movement of a mass object (m) and speed (v) will be equal to the product of the mass by speed. On the other hand, an applied force on the body in motion will increase or decrease its amount of movement, depending on whether it acts for or against the direction of the movement. On the contrary, when a mass does not vary during movement, it means that the speeds are much lower than the light, considering the amount of mass of the object under study, as constant. Therefore, this law is considered as the cornerstone of mechanics and is perhaps the most important principle of all physics.

Third Law (Law of Action and Reaction) This third movement law allows to consolidate the understanding of the concept of force. Where Newton mentions that “for all action there is always an opposite and equal reaction. The reciprocal actions of two bodies among themselves are always equal and directed towards contrary parts ”. This means that anything that drags or confirms to another is equally dragged or compressed by that other. Since, if one body stumbles with another, and due to its strength, it changes its movement, he will also undergo an equal change in his own movement towards the opposite part. Thus, the changes produced by these actions are not equal in the speeds, however, if in the movements of the bodies, provided that they are not hindered by any other impediment.

However, Newton’s third law differs from others in a relevant aspect, and that is that in the first and the second law the behavior of a specific and unique body is treated, so the third law implies two different bodiesAnd separated, in this way it can be interpreted that forces are always going to be presented in pairs, or, it is possible that there is an isolated force.

Since, the forces that act on a body result from other bodies that make up its surroundings, thus, the force is considered part of a mutual interaction between two or more bodies. Therefore, it is common that there are difficulties in the correct interpretation of this law, especially considering that the action and reaction forces will always act on different bodies.

Of these three laws he deduced a fourth, which is the best known: the law of gravity, which Newton himself told his friend and biographer William Stukeley (it turns out that the anecdote is true), was suggested by the observation ofThe fall of an apple from the tree.

In addition, Newton discovered that the force of attraction between Earth and the Moon was directly proportional to the product of its masses and inversely proportional to the square of the distance that separated them;By extending that general principle to all the bodies of the universe he turned his law of gravity into the Law of Universal Gravitation. Most of these ideas already circulated through the scientific environments of the time, but Newton gave him the character of a general theory capable of scientifically explaining the universe together.

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