CLASSICAL MECHANICS
Specificity of Newton's laws for objects with variable mass
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Isaac Newton
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Sir Isaac Newton, (December 25, 1642 - March 20, 1727 by
the Julian calendar then in use; or January 4, 1643 - March 31, 1727
by the Gregorian calendar) was an English alchemist, mathematician, scientist
and philosopher; who published the Philosophiae Naturalis Principia Mathematica
(1687), where he described universal gravitation and, via his laws of
motion, laid the groundwork for classical mechanics. Newton also shares
credit with Gottfried Wilhelm Leibniz for the development of differential
calculus. |
Further Accomplishments
Newton was the first to demonstrate that natural laws govern earthly motion and celestial motion. He is associated with the Scientific Revolution and the advancement of heliocentrism. Newton is also credited with providing mathematical substantiation for Kepler's laws of planetary motion. He would expand these laws by arguing that orbits (such as those of comets) were not only elliptic; but could also be hyperbolic and parabolic. In addition, Newton is credited with being the first to demonstrate that white light is a composite, or mixture, of the other colourss. He is also notable for his arguments that light was composed of particles.
Biography
Newton was born in Woolsthorpe-by-Colsterworth, a hamlet in the county of Lincolnshire. His father had died three months before Newton's birth, and two years later his mother went to live with her new husband, leaving her son in the care of his grandmother.
Newton was educated at Grantham Grammar School. In 1661 he joined Trinity College, Cambridge, where his uncle William Ayscough had studied. At that time the college's teachings were based on those of Aristotle, but Newton preferred to read the more advanced ideas of modern philosophers such as Descartes, Galileo, Copernicus and Kepler. In 1665 he discovered the binomial theorem and began to develop a mathematical theory that would later become calculus. Soon after Newton had collected his degree in 1665, the University closed down as a precaution against the Great Plague. For the next two years Newton worked at home on calculus, optics and gravitation.
Tradition has it that Newton was sitting under an apple tree when an apple fell on his head, and this made him understand that earthly and celestial gravitation are the same. This is an exaggeration of Newton's own tale about sitting by the window of his home (Woolsthorpe Manor) and watching an apple fall from a tree. However it is now generally considered that even this story was invented by him in his later life, to try to show how clever he was at drawing inspiration from everyday events. A contemporary writer, William Stukeley, recorded in his Memoirs of Sir Isaac Newton's Life a conversation with Newton in Kensington on April 15 1726, in which Newton recalled "when formerly, the notion of gravitation came into his mind. It was occasioned by the fall of an apple, as he sat in contemplative mood. Why should that apple always descend perpendicularly to the ground, thought he to himself. Why should it not go sideways or upwards, but constantly to the earth's centre."
Newton became a fellow of Trinity College in 1667. In the same year he circulated his findings in De Analysi per Aequationes Numeri Terminorum Infinitas (On Analysis by Infinite Series), and later in De methodis serierum et fluxionum (On the Methods of Series and Fluxions), whose title gave the name to his "method of fluxions".
Newton and Leibniz developed the theory of calculus independently and used different notations. Although Newton had worked out his own method before Leibniz, the latter's notation and "Differential Method" were superior, and were generally adopted. Though Newton belongs among the brightest scientists of his era, the last twenty-five years of his life were marred by a bitter dispute with Leibniz, whom he accused of plagiarism.
He was elected Lucasian professor of mathematics in 1669. This position exempted him from having to enter the church in order to remain a Fellow of the college, and prevented the conflict that would have occurred between his anti-Trinitarian views and the orthodoxy of the church.
Writings by Newton