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In physics, the history of centrifugal and centripetal forces illustrates a long and complex evolution of thought about the nature of forces, relativity, and the nature of physical laws. ==Huygens, Leibniz, Newton, and Hooke== Early scientific ideas about centrifugal force were based upon intuitive perception, and circular motion was considered somehow more "natural" than straight-line motion. According to Domenico Bertoloni-Meli: :"For Huygens and Newton centrifugal force was the result of a curvilinear motion of a body; hence it was located in nature, in the object of investigation. According to a more recent formulation of classical mechanics, centrifugal force depends on the choice of how phenomena can be conveniently represented. Hence it is not located in nature, but is the result of a choice by the observer. In the first case a mathematical formulation mirrors centrifugal force; in the second it creates it."〔 〕 Christiaan Huygens coined the term "centrifugal force" in his 1659 ''De Vi Centrifuga''〔 〕 and wrote of it in his 1673 ''Horologium Oscillatorium'' on pendulums. Isaac Newton coined the term "centripetal force" (''vis centripita'') in his discussions of gravity in his 1684 ''De Motu Corporum''.〔 〕 Gottfried Leibniz as part of his "solar vortex theory" conceived of centrifugal force as a real outward force which is induced by the circulation of the body upon which the force acts. An inverse cube law centrifugal force appears in an equation representing planetary orbits, including non-circular ones, as Leibniz described in his 1689 ''Tentamen de motuum coelestium causis''.〔 〕 Leibniz's equation is still used today to solve planetary orbital problems, although his solar vortex theory is no longer used as its basis.〔 〕 Leibniz produced an equation for planetary orbits in which the centrifugal force appeared as an outward inverse cube law force in the radial direction:〔 〕 :. Newton himself appears to have previously supported an approach similar to that of Leibniz.〔 Later, Newton in his ''Principia'' crucially limited the description of the dynamics of planetary motion to a frame of reference in which the point of attraction is fixed. In this description, Leibniz's centrifugal force was not needed and was replaced by only continually inward forces toward the fixed point.〔 Newton objected to Leibniz's equation on the grounds that it allowed for the centrifugal force to have a different value from the centripetal force, arguing on the basis of his third law of motion, that the centrifugal force and the centripetal force must constitute an equal and opposite action-reaction pair. In this however, Newton was mistaken, as the reactive centrifugal force which is required by the third law of motion is a completely separate concept from the centrifugal force of Leibniz's equation.〔 〕〔 (【引用サイトリンク】title=Newton, Sir Isaac )〕 Huygens, who was, along with Leibniz, a neo-Cartesian and critic of Newton, concluded after a long correspondence that Leibniz's writings on celestial mechanics made no sense, and that his invocation of a harmonic vortex was logically redundant, because Leibniz's radial equation of motion follows trivially from Newton's laws. Even the most ardent modern defenders of the cogency of Leibniz's ideas acknowledge that his harmonic vortex as the basis of centrifugal force was dynamically superfluous.〔A. R. Hall, Philosophers at War, 2002, pp 150-151〕 It has been suggested that the idea of circular motion as caused by a single force was introduced to Newton by Robert Hooke.〔 Newton described the role of centrifugal force upon the height of the oceans near the equator in the ''(Principia )'': The effect of centrifugal force in countering gravity, as in this behavior of the tides, has led centrifugal force sometimes to be called "false gravity" or "imitation gravity" or "quasi-gravity".〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「History of centrifugal and centripetal forces」の詳細全文を読む スポンサード リンク
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