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D'Alembert's
Jean-Baptiste le Rond d'Alembert (; ; 16 November 1717 – 29 October 1783) was a French mathematician, mechanician, physicist, philosopher, and music theorist. Until 1759 he was, together with Denis Diderot, a co-editor of the ''Encyclopédie''. D'Alembert's formula for obtaining solutions to the wave equation is named after him. The wave equation is sometimes referred to as d'Alembert's equation, and the fundamental theorem of algebra is named after d'Alembert in French. Early years Born in Paris, d'Alembert was the natural son of the writer Claudine Guérin de Tencin and the chevalier Louis-Camus Destouches, an artillery officer. Destouches was abroad at the time of d'Alembert's birth. Days after birth his mother left him on the steps of the church. According to custom, he was named after the patron saint of the church. D'Alembert was placed in an orphanage for foundling children, but his father found him and placed him with the wife of a glazier, Madame Rousseau, with who ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
D'Alembert's Principle
D'Alembert's principle, also known as the Lagrange–d'Alembert principle, is a statement of the fundamental classical laws of motion. It is named after its discoverer, the French physicist and mathematician Jean le Rond d'Alembert. D'Alembert's principle generalizes the principle of virtual work from static to dynamical systems by introducing ''forces of inertia'' which, when added to the applied forces in a system, result in ''dynamic equilibrium''. The principle does not apply for irreversible displacements, such as sliding friction, and more general specification of the irreversibility is required. D'Alembert's principle is more general than Hamilton's principle as it is not restricted to holonomic constraints that depend only on coordinates and time but not on velocities. Statement of the principle The principle states that the sum of the differences between the forces acting on a system of massive particles and the time derivatives of the momenta of the system itself ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Work
In mechanics, virtual work arises in the application of the ''principle of least action'' to the study of forces and movement of a mechanical system. The work of a force acting on a particle as it moves along a displacement is different for different displacements. Among all the possible displacements that a particle may follow, called virtual displacements, one will minimize the action. This displacement is therefore the displacement followed by the particle according to the principle of least action. The work of a force on a particle along a virtual displacement is known as the virtual work. Historically, virtual work and the associated calculus of variations were formulated to analyze systems of rigid bodies, but they have also been developed for the study of the mechanics of deformable bodies. History The principle of virtual work had always been used in some form since antiquity in the study of statics. It was used by the Greeks, medieval Arabs and Latins, and Renais ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
D'Alembert Force
A fictitious force is a force that appears to act on a mass whose motion is described using a non-inertial frame of reference, such as a linearly accelerating or rotating reference frame. It is related to Newton's second law of motion, which treats forces for just one object. Passengers in a vehicle accelerating in the forward direction may perceive they are acted upon by a force moving them into the direction of the backrest of their seats for example. An example in a rotating reference frame may be the impression that it is a force which seems to move objects outward toward the rim of a centrifuge or carousel. The fictitious force called a pseudo force might also be referred to as a body force. It is due to an object's inertia when the reference frame does not move inertially any more but begins to accelerate relative to the free object. In terms of the example of the passenger vehicle, a pseudo force seems to be active just before the body touches the backrest of the seat in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Denis Diderot
Denis Diderot (; ; 5 October 171331 July 1784) was a French philosopher, art critic, and writer, best known for serving as co-founder, chief editor, and contributor to the ''Encyclopédie'' along with Jean le Rond d'Alembert. He was a prominent figure during the Age of Enlightenment. Diderot initially studied philosophy at a Jesuit college, then considered working in the church clergy before briefly studying law. When he decided to become a writer in 1734, his father disowned him. He lived a bohemian existence for the next decade. In the 1740s he wrote many of his best-known works in both fiction and non-fiction, including the 1748 novel ''The Indiscreet Jewels''. In 1751, Diderot co-created the ''Encyclopédie'' with Jean le Rond d'Alembert. It was the first encyclopedia to include contributions from many named contributors and the first to describe the mechanical arts. Its secular tone, which included articles skeptical about Biblical miracles, angered both religious and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
D'Alembert's Paradox
In fluid dynamics, d'Alembert's paradox (or the hydrodynamic paradox) is a contradiction reached in 1752 by French mathematician Jean le Rond d'Alembert. D'Alembert proved that – for incompressible and inviscid potential flow – the drag force is zero on a body moving with constant velocity relative to the fluid.Grimberg, Pauls & Frisch (2008). Zero drag is in direct contradiction to the observation of substantial drag on bodies moving relative to fluids, such as air and water; especially at high velocities corresponding with high Reynolds numbers. It is a particular example of the reversibility paradox. D’Alembert, working on a 1749 Prize Problem of the Berlin Academy on flow drag, concluded: ''"It seems to me that the theory (potential flow), developed in all possible rigor, gives, at least in several cases, a strictly vanishing resistance, a singular paradox which I leave to future Geometers .e. mathematicians - the two terms were used interchangeably at that timeto e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyclopédie
''Encyclopédie, ou dictionnaire raisonné des sciences, des arts et des métiers'' (English: ''Encyclopedia, or a Systematic Dictionary of the Sciences, Arts, and Crafts''), better known as ''Encyclopédie'', was a general encyclopedia published in France between 1751 and 1772, with later supplements, revised editions, and translations. It had many writers, known as the Encyclopédistes. It was edited by Denis Diderot and, until 1759, co-edited by Jean le Rond d'Alembert. The ''Encyclopédie'' is most famous for representing the thought of the Enlightenment. According to Denis Diderot in the article "Encyclopédie", the ''Encyclopédies aim was "to change the way people think" and for people (bourgeoisie) to be able to inform themselves and to know things. He and the other contributors advocated for the secularization of learning away from the Jesuits. Diderot wanted to incorporate all of the world's knowledge into the ''Encyclopédie'' and hoped that the text could dissemina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate causes of phenomena, and usually frame their understanding in mathematical terms. Physicists work across a wide range of research fields, spanning all length scales: from sub-atomic and particle physics, through biological physics, to cosmological length scales encompassing the universe as a whole. The field generally includes two types of physicists: experimental physicists who specialize in the observation of natural phenomena and the development and analysis of experiments, and theoretical physicists who specialize in mathematical modeling of physical systems to rationalize, explain and predict natural phenomena. Physicists can apply their knowledge towards solving practical problems or to developing new technologies (also known as applie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanics
Mechanics (from Ancient Greek: μηχανική, ''mēkhanikḗ'', "of machines") is the area of mathematics and physics concerned with the relationships between force, matter, and motion among physical objects. Forces applied to objects result in displacements, or changes of an object's position relative to its environment. Theoretical expositions of this branch of physics has its origins in Ancient Greece, for instance, in the writings of Aristotle and Archimedes (see History of classical mechanics and Timeline of classical mechanics). During the early modern period, scientists such as Galileo, Kepler, Huygens, and Newton laid the foundation for what is now known as classical mechanics. As a branch of classical physics, mechanics deals with bodies that are either at rest or are moving with velocities significantly less than the speed of light. It can also be defined as the physical science that deals with the motion of and forces on bodies not in the quantum realm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Dynamics
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids— liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation. Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a fluid dynamics problem typically involves the calculation of various properties of the fluid, such as flow velocity, pressure, density, and temperature, as functions of space and time. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Music Theorist
Music theory is the study of the practices and possibilities of music. ''The Oxford Companion to Music'' describes three interrelated uses of the term "music theory". The first is the "rudiments", that are needed to understand music notation (key signatures, time signatures, and rhythmic notation); the second is learning scholars' views on music from antiquity to the present; the third is a sub-topic of musicology that "seeks to define processes and general principles in music". The musicological approach to theory differs from music analysis "in that it takes as its starting-point not the individual work or performance but the fundamental materials from which it is built." Music theory is frequently concerned with describing how musicians and composers make music, including tuning systems and composition methods among other topics. Because of the ever-expanding conception of what constitutes music, a more inclusive definition could be the consideration of any sonic phenomena, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Random House Webster's Unabridged Dictionary
''Random House Webster's Unabridged Dictionary'' is a large American dictionary, first published in 1966 as ''The Random House Dictionary of the English Language: The Unabridged Edition''. Edited by Editor-in-chief Jess Stein, it contained 315,000 entries in 2256 pages, as well as 2400 illustrations. The CD-ROM version in 1994 also included 120,000 spoken pronunciations. History The Random House publishing company entered the reference book market after World War II. They acquired rights to the ''Century Dictionary'' and the ''Dictionary of American English'', both out of print. Their first dictionary was Clarence Barnhart's ''American College Dictionary'', published in 1947, and based primarily on ''The New Century Dictionary'', an abridgment of the ''Century''. In the late 1950s, it was decided to publish an expansion of the ''American College Dictionary'', which had been modestly updated with each reprinting since its publication. Under editors Jess Stein and Laurence Ur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Institut De France
The (; ) is a French learned society, grouping five , including the Académie Française. It was established in 1795 at the direction of the National Convention. Located on the Quai de Conti in the 6th arrondissement of Paris, the institute manages approximately 1,000 foundations, as well as museums and châteaux open for visit. It also awards prizes and subsidies, which amounted to a total of over €27 million per year in 2017. Most of these prizes are awarded by the institute on the recommendation of the . History The building was originally constructed as the Collège des Quatre-Nations by Cardinal Mazarin, as a school for students from new provinces attached to France under Louis XIV. The inscription over the façade reads "JUL. MAZARIN S.R.E. CARD BASILICAM ET GYMNAS F.C.A M.D.C.LXI", attesting that Mazarin ordered its construction in 1661. The Institut de France was established on 25 October 1795, by the National Convention. On 1 January 2018, Xavier Darcos took ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
