Newton's laws of motion constitute the essence of classical mechanics.
Classical mechanics is the name that has become popular to distinguish a branch of physics whose focus is on accurately evaluating how macroscopic physical bodies behave, both at rest and at a certain speed .
In this area of study that connects movement with the force and acceleration of a body, the physical laws are understood by scientific determinism , the principle of least action is essential when analyzing the temporal evolution of a system and time is conceived as absolute .
It is interesting to remember that originally (that is, before being subjected to reformulation processes), classical mechanics was based on notions arising from Isaac Newton 's research, findings and postulates about the movement of bodies . At this point it is necessary to emphasize that this English mathematician, inventor and physicist formulated the law of universal gravitation and we owe him, among other relevant issues, the principle of inertia , the fundamental law of dynamics and the principle of action and reaction .
Branches of classical mechanics
By gathering information related to the scope, formulations and approaches of classical mechanics, multiple branches come to light.
This discipline is enriched, for example, by approaches and reformulations that give identity to the so-called Lagrangian mechanics ( Joseph-Louis de Lagrange's vital contribution to simplifying physical problems or challenges that can be solved using Lagrange's equations ), Hamiltonian mechanics (whose name alludes to William R. Hamilton ) and Newtonian mechanics (the latter is also often referred to as vector mechanics ). There is even analytical mechanics .
Popularly, however, there are three large groups that feed this variety of mechanics : kinematics , dynamics and statics .
It is also useful to know what statistical mechanics , celestial mechanics , relativistic mechanics and continuum mechanics are and what they are used for.
When studying the movement of a body, it is important to know that speed and acceleration are two concepts that, although linked, are different.
Basic principles
Classical mechanics is based on a series of basic principles that we will list below.
One of them is the principle of least action (also known as Hamilton's principle ), a key postulate to explain how, over time, the condition of motion of a certain particle evolves. This reasoning can be proven, in particular, thanks to Newton's laws of motion .
There is also an absolute time , a magnitude that marks a uniform measure for all observers, regardless of the degree that each one exhibits in terms of movement.
Knowing the position and the percentage of movement of a particle , on the other hand, its state is deduced since it is determined and, in this context, the principle of causality comes into play.
As can be seen from the theory, multiple formulations are allowed within classical mechanics , each of which proposes an approximation to more precise laws of nature. However, speeds that do not equal or exceed the speed of light must always be considered (they must be significantly lower than the speed of light ) and the sizes studied must be above 1 nm.
Experts in this discipline point out the need to appeal to quantum mechanics to adapt the equations of Hamilton, Lagrange or Newton if one intends to work with microscopic elements. It is even necessary to know what is, or where is, the band that marks the limit between the aforementioned classical mechanics and another one based on the theory of relativity that, for that reason, has been baptized as relativistic mechanics .
The principles of classical mechanics help, for example, to predict how billiard balls move.
Examples of classical mechanics
Classical mechanics serves, to describe an example case, to generate a solid explanation regarding phenomena and movements evident in the solar system . It is appropriate to point out in this framework that Galileo Galilei was one of the many who have made studies focused on movement: in his case, to detail one of his works, he developed a theory on tides that came to contradict the principle of inertia but sought to prove that the tides were a consequence of the movement of the planet Earth .
From an empirical approach to mechanical science, it is also possible to experimentally measure the speed reached, in different instances, by a small ball (for example, like the one used to play golf) that, after remaining at rest , falls from a certain height. This test, which invites us to appreciate what a free fall consists of, involves factors or magnitudes such as time , speed , gravity and acceleration .
In short, many experiments or situations that involve the movement of a body with macroscopic characteristics, encompassing concepts such as energy , linear momentum and mechanical work, are demonstrated and explained thanks to classical mechanics . Due to its characteristics, it is a necessary and ideal discipline for predicting how a system or device will behave or for the design process of machinery oriented to the forces of movement .