Information On mechanics

Mechanics (Greek language {{Polytonic|Μηχανική}} is the branch of physics concerned with the behavior of physical body when subjected to force or Displacement (vector) and the subsequent effects of the bodies on their environment. The discipline has its roots in several ancient civilizations (see History of classical mechanics and Timeline of classical mechanics . During the early modern period scientists such as Galileo Johannes Kepler and especially Isaac Newton laid the foundation for what is now known as classical mechanics The system of study of mechanics is shown in the table below: File:Mechanics Overview Table.jpg

Classical versus quantum

The major division of the mechanics discipline separates classical mechanics from quantum mechanics Historically, classical mechanics came first, while quantum mechanics is a comparatively recent invention. Classical mechanics originated with Isaac Newton s Laws of motion in Philosophiæ Naturalis Principia Mathematica while quantum mechanics didnt appear until 1900. Both are commonly held to constitute the most certain knowledge that exists about physical nature. Classical mechanics has especially often been viewed as a model for other so-called exact science . Essential in this respect is the relentless use of mathematics in theories, as well as the decisive role played by experiment in generating and testing them. Quantum mechanics is of a wider scope, as it encompasses classical mechanics as a sub-discipline which applies under certain restricted circumstances. According to the correspondence principle there is no contradiction or conflict between the two subjects, each simply pertains to specific situations. The correspondence principle states that the behavior of systems described by quantum theories reproduces classical physics in the limit of large quantum numbers. Quantum mechanics has superseded classical mechanics at the foundational level and is indispensable for the explanation and prediction of processes at molecular and (sub)atomic level. However, for macroscopic processes classical mechanics is able to solve problems which are unmanageably difficult in quantum mechanics and hence remains useful and well used.

Einsteinian versus Newtonian

Analogous to the quantum versus classical reformation, Einstein s General relativity and Special relativity theories of theory of relativity have expanded the scope of mechanics beyond the mechanics of Issac Newton and Galileo and made fundamental corrections to them, that become significant and even dominant as speeds of material objects approach the speed of light which cannot be exceeded. Relativistic corrections are also needed for quantum mechanics, although General relativity has not been integrated; the two theories remain incompatible, a hurdle which must be overcome in developing the Grand Unified Theory

History

Antiquity

The main theory of mechanics in antiquity was Aristotelian mechanics "[http://books.google.com/books?id=vPT-JubW-7QC&pg=PA19&dq&hl=en#v=onepage&q=&f=false A history of mechanics]. René Dugas (1988). p.19. ISBN 0486656322 A later developer in this tradition was Hipparchus "http://golem.ph.utexas.edu/category/2008/01/a_tiny_taste_of_the_history_of.html A Tiny Taste of the History of Mechanics]". The University of Texas at Austin.

Medieval age

In the Middle Ages, Aristotles theories were criticized and modified by a number of figures, beginning with John Philoponus in the 6th century, and reaching its peak during the Golden Age of Islam A central problem was that of projectile motion which was discussed by Hipparchus and Philoponus. This led to the development of the theory of impetus by 14th century French Jean Buridan which developed into the modern theories of inertia velocity acceleration and momentum This work and others was developed in 14th century England by the Oxford Calculators such as Thomas Bradwardine who studied and formulated various laws regarding falling bodies. On the question of a body subject to a constant (uniform) force, the 12th century Jewish-Arab Hibat Allah Abu'l-Barakat al-Baghdaadi (Iraqi, of Baghdad) stated that constant force imparts constant acceleration, while the main properties are uniformly accelerated motion (as of falling bodies) was worked out by the 14th century Oxford Calculators.

Early modern age

Two central figures in the early modern age are Galileo Galilei and Isaac Newton Galileos final statement of his mechanics, particularly of falling bodies, is his [[Two New Sciences]](1638). Newtons 1687 [[Philosophiæ Naturalis Principia Mathematica]]provided a detailed mathematical account of mechanics, using the newly developed mathematics of calculus and providing the basis of Newtonian mechanics There is some dispute over priority of various ideas: Newtons Principiais certainly the seminal work and has been tremendously influential, and the systematic mathematics therein did not and could not have been stated earlier because calculus had not been developed. However, many of the ideas, particularly as pertain to inertia (impetus) and falling bodies had been developed and stated by earlier researchers, both the then-recent Galileo and the less-known medieval predecessors. Precise credit is at times difficult or contentious because scientific language and standards of proof changed, so whether medieval statements are equivalentto modern statements or sufficientproof, or instead similarto modern statements and hypothesesis often debatable.

Modern age

Two main modern developments in mechanics are general relativity of Einstein, and quantum mechanics, both developed in the 20th century based in part on earlier 19th century ideas.

Types of mechanical bodies

Thus the often-used term [[Physical body|body]] needs to stand for a wide assortment of objects, including particles, projectiles spacecraft star , parts of mechanical engineering parts of solids parts of fluids (gases and liquids , etc. Other distinctions between the various sub-disciplines of mechanics, concern the nature of the bodies being described. Particles are bodies with little (known) internal structure, treated as mathematical points in classical mechanics. Rigid bodies have size and shape, but retain a simplicity close to that of the particle, adding just a few so-called degrees of freedom (physics and chemistry) such as orientation in space. Otherwise, bodies may be semi-rigid, i.e. Elasticity (physics) or non-rigid, i.e. fluid These subjects have both classical and quantum divisions of study. For instance, the motion of a spacecraft, regarding its orbit and attitude (rotation , is described by the relativistic theory of classical mechanics, while the analogous movements of an atomic nucleus are described by quantum mechanics.

Sub-disciplines in mechanics

The following are two lists of various subjects that are studied in mechanics. Note that there is also the "Field theory (physics) which constitutes a separate discipline in physics, formally treated as distinct from mechanics, whether classical electromagnetism or quantum field theory But in actual practice, subjects belonging to mechanics and fields are closely interwoven. Thus, for instance, forces that act on particles are frequently derived from fields (Electromagnetism or gravitational , and particles generate fields by acting as sources. In fact, in quantum mechanics, particles themselves are fields, as described theoretically by the wave function

Classical mechanics

The following are described as forming Classical mechanics: * Newtonian mechanics the original theory of motion (kinematics and forces (Analytical dynamics * Hamiltonian mechanics a theoretical formalism based on the principle of conservation of energy * Lagrangian mechanics another theoretical formalism, based on the principle of the least action * Celestial mechanics the motion of heavenly bodies: planets, comets, stars, galaxies etc. * Astrodynamics spacecraft navigation etc. * Solid mechanics Elasticity (physics) the properties of deformable bodies * Acoustics sound ( density variation propagation) in solids, fluids and gases. * Statics semi-rigid bodies in mechanical equilibrium * Fluid mechanics the motion of fluids * Soil mechanics mechanical behavior of soils * Continuum mechanics mechanics of continua (both solid and fluid) * Hydraulics mechanical properties of liquids * Fluid statics liquids in equilibrium * Applied mechanics * Biomechanics solids, fluids, etc. in biology * Biophysics physical processes in living organisms * Statistical mechanics assemblies of particles too large to be described in a deterministic way * Relativistic or Albert Einstein mechanics, universal gravitation

Quantum mechanics

The following are categorized as being part of Quantum mechanics * Particle physics the motion, structure, and reactions of particles * Nuclear physics the motion, structure, and reactions of nuclei * Condensed matter physics quantum gases, solids, liquids, etc. * Quantum statistical mechanics large assemblies of particles

Professional organizations

*Applied Mechanics Division American Society of Mechanical Engineers *Fluid Dynamics Division, American Physical Society *http://www.imeche.org Institution of Mechanical Engineers] is the United Kingdoms qualifying body for Mechanical Engineers and has been the home of Mechanical Engineers for over 150 years. *http://www.iutam.net/ International Union of Theoretical and Applied Mechanics]

See also

*Analytical mechanics *Applied mechanics *Dynamical system *Engineering *Kinematics *Kinetics

References

Further reading

*

External links

* http://iMechanica.org/ iMechanica: the web of mechanics and mechanicians] * http://rodsalgado.blogspot.com/ Mechanics Blog by a Purdue University Professor] * http://www.esm.vt.edu/ The Mechanics program at Virginia Tech] * http://www.physclips.unsw.edu.au/ Physclips: Mechanics with animations and video clips] from the University of New South Wales * http://www7.nationalacademies.org/usnctam U.S. National Committee on Theoretical and Applied Mechanics] * http://www.physics-online.com Interactive learning resources for teaching Mechanics] Category:Mechanics Category:Greek loanwords af:Meganika ar:ميكانيكا az:Mexanika bn:বলবিদ্যা be-x-old:Мэханіка bg:Механика ca:Mecànica cs:Mechanika da:Mekanik de:Mechanik et:Mehaanika el:Μηχανική es:Mecánica eo:Mekaniko eu:Mekanika fa:مکانیک fr:Mécanique (science) ga:Meicnic gl:Mecánica ko:역학 (물리학) hi:यांत्रिकी hr:Mehanika io:Mekaniko id:Mekanika ia:Mechanica it:Meccanica (fisica) ka:მექანიკა lv:Mehānika lb:Mechanik lt:Mechanika hu:Mechanika mk:Механика nl:Mechanica ja:力学 no:Mekanikk km:មេកានិច pms:Mecànica pl:Mechanika kaa:Mexanika ro:Mecanică ru:Механика stq:Mechanik sq:Mekanika simple:Mechanics sk:Mechanika sl:Mehanika ckb:میکانیک sr:Механика sh:Mehanika fi:Mekaniikka sv:Mekanik ta:விசையியல் tr:Mekanik uk:Механіка ur:آلاتیات wo:Doolerandu wuu:力学 yi:מעכאניק zh:力学

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