In classical physics, mechanical movement is the physical phenomenon that is defined as any change of position in space experienced by the bodies of a system with respect to themselves or to another body that is taken as a reference. Every body in motion describes a path. The description and study of the movement of a body requires determining its position in space as a function of time. For this, a reference or referential system is necessary.
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- 1 History
- 2 Newton’s Laws
- 1 Newton’s First Law or Law of Inertia
- 2 Newton’s Second Law or Law of Force
- 3 Newton’s Third Law or Law of action and reaction
- 3 Types of movement
- 1 Uniform rectilinear motion
- 2 Uniformly accelerated rectilinear motion
- 3 Circular motion
- 4 Wave motion
- 5 Parabolic motion
- 6 Pendulum movement
- 7 Simple harmonic motion
- 4 Source
Mechanics encompasses a wide range of characters that throughout their lives have been giving important contributions to the evolution of this area. Before delving into the ancient beginnings of this discipline, it is important to know that mechanics is a science that is responsible for studying the conditions of rest or movement of bodies under the action of forces.
Besides this, mechanics as a science appeared in the Hellenistic period and it was Archimedes, who quantitatively described the laws of the lever and other simple machines, which with their use gave rise to the first notions of dynamics and statics. Archimedes laid the foundations of statics and was the founder of hydrostatics by enunciating its famous principle. In addition to Archimedes over the years, there were also other physics scholars who gradually served as an impetus by providing valuable principles for the development of mechanics among them. Tartaglia, Galileo Galilei, Newton, Euler, Einstein, among others, can be cited.
The Italian physicist and astronomer Galileo gathered the ideas of other great thinkers of his time and began to analyze motion based on the distance traveled from a starting point and the time elapsed. It showed that the speed of falling objects increases continuously during their fall. This acceleration is the same for heavy or light objects, provided that air resistance (friction) is not taken into account.
British mathematician and physicist Isaac Newton improved this analysis by defining force and mass, and relating them to acceleration. For objects moving at speeds close to the speed of light , Newton’s laws have been replaced by Albert Einstein’s theory of relativity . For atomic and subatomic particles, Newton’s laws have been replaced by quantum mechanics . But for the phenomena of daily life, Newton’s three laws of motion constitute the cornerstone of dynamics (the study of the causes of change in motion).
Movement is present in almost everything around us (Humans, animals and countless parts of them move; water from rivers and seas; air by forming winds; means of transportation; parts of mechanisms ; Earth; celestial bodies such as planets, stars and galaxies; molecules and atoms ), so it has countless practical applications. His study allows: describe them, design them with the desired characteristics.
Newton’s Laws, also known as Newton’s Laws of Motion, are three principles from which most of the problems posed by dynamics are explained, particularly those related to the motion of bodies. They revolutionized the basic concepts of physics and the movement of bodies in the universe. As they form the foundations not only of classical dynamics but also of classical physics in general. Although they include certain definitions and in a certain sense can be seen as axioms, Newton affirmed that they are based on observations and quantitative experiments; they certainly cannot be derived from other, more basic relationships. The proof of their validity lies in their predictions and the validity of those predictions was verified in each and every case for more than two centuries. The studies that he carried out can be defined with the following three laws that he postulated:
Newton’s First Law or Law of Inertia
The first law of motion refutes the Aristotelian idea that a body can only keep moving if a force is applied to it. Newton states that: Every body perseveres in its state of rest or rectilinear uniform movement unless it is forced to change its state by forces imprinted on it. This law postulates, therefore, that a body cannot change its initial state by itself, either at rest or in uniform rectilinear motion, unless a force or a series of forces is applied whose result is not null on it. Newton takes into account, thus, that moving bodies are constantly subjected to friction or friction forces, which slows them down progressively, something new with respect to previous conceptions that understood that the movement or arrest of a body was exclusively due to the fact that a force was exerted on them, but never understanding friction as this. Consequently, a body with uniform rectilinear motion implies that there is no net external force or, in other words, a moving object does not stop naturally if a force is not applied to it. In the case of bodies at rest, it is understood that their speed is zero, so if it changes it is because a net force has been exerted on that body. A moving object does not stop naturally if a force is not applied to it. In the case of bodies at rest, it is understood that their speed is zero, so if it changes it is because a net force has been exerted on that body. A moving object does not stop naturally if a force is not applied to it. In the case of bodies at rest, it is understood that their speed is zero, so if it changes it is because a net force has been exerted on that body.
Newton’s Second Law or Law of Force
Newton’s second law of motion says: The change in motion is proportional to the printed driving force and occurs along the straight line along which that force is printed. This law explains what happens if a net force acts on a body in motion (whose mass does not have to be constant): the force will modify the state of movement, it will change the speed in module or direction. Specifically, the changes experienced in the amount of movement of a body are proportional to the driving force and develop in its direction; that is, forces are causes that cause accelerations in the bodies. Consequently, there is a relationship between cause and effect, that is, force and acceleration are related. Synthetically said,
Newton’s Third Law or Law of Action and Reaction
Newton’s third law states: With every action an equal and opposite reaction always occurs: that is, the mutual actions of two bodies are always equal and directed in the opposite direction. The third law is completely original to Newton (since the first two were proposed in other ways by Galileo, Hooke and Huygens) and makes the laws of mechanics a complete and logical set. He explains that for every force acting on a body, it performs a force of equal intensity and direction, but in the opposite direction on the body that produced it. In other words, the forces, located on the same line, always appear in pairs of equal magnitude and opposite in direction. It is important to note that this principle of action and reaction relates two forces that are not applied to the same body, and produce different accelerations in them, according to their masses. Otherwise, each of these forces obeys the second law separately. Together with the previous laws, this allows the principles of conservation of linear momentum and angular momentum to be stated.
Types of movement
Uniform line movement
A movement is rectilinear when it describes a straight and uniform trajectory and its speed is constant in time, that is, its acceleration is zero. This implies that the average speed between any two instants will always have the same value. Furthermore, the instantaneous and average speed of this movement will coincide.
Uniformly accelerated rectilinear motion
Uniformly accelerated rectilinear motion is one in which a body moves on a line with constant acceleration. This implies that in any time interval, the acceleration of the body will always have the same value. For example, the free fall of a body, with acceleration of constant gravity.
Circular motion is one based on a constant radius of rotation: the path will be a circumference. If, in addition, the speed of rotation is constant, uniform circular motion occurs, which is a particular case of circular motion, with fixed radius and constant angular velocity. It cannot be said that the speed is constant since, being a vector quantity, it has modulus, direction and direction: the modulus of the speed remains constant throughout the movement but the direction changes constantly, it is at all times tangent to the path circular. This implies the presence of an acceleration that, although in this case the speed modulus does not vary, its direction does change.
An undulatory movement is the one made by an object whose path describes an undulation. It corresponds to the ideal path of a body moving in a medium that offers no resistance to advance and is subject to a uniform gravitational field. It is also possible to demonstrate that it can be analyzed as the composition of two rectilinear movements, a horizontal uniform rectilinear movement and a uniformly accelerated vertical rectilinear movement.
Parabolic motion refers to the movement made by an object whose trajectory describes a parabola. It corresponds to the ideal path of a body that moves in a medium, that does not offer resistance to advance and that is subject to a uniform gravitational field. It is also possible to demonstrate that it can be analyzed as the composition of two rectilinear movements, a horizontal uniform rectilinear movement and a uniformly accelerated vertical rectilinear movement.
Pendulum motion is a form of displacement that some physical systems present as a practical application to simple harmonic motion. There are characteristics of the pendulum movement according to the simple pendulum, torsion pendulum and physical pendulum.
Simple harmonic motion
Simple harmonic motion (abbreviated more), also called simple harmonic vibratory motion (abbreviated mvas), is a periodic motion that is described as a function of time by a harmonic function (sine or cosine). If the description of a movement required more than one harmonic function, in general it would be a harmonic movement, but not one more.
In the case that the trajectory is rectilinear, the particle that performs one more oscillates away and towards a point, located in the center of its trajectory, in such a way that its position as a function of time with respect to that point is a sinusoid. . In this movement, the force acting on the particle is proportional to its movement with respect to said point and directed towards it.