Isaac Newton
Sir Isaac Newton: Physics, Gravity, and Laws of MotionBy Cynthia Stokes BrownNewton developed the three basic laws of motion and the theory of universal gravity, which together laid the foundation for our current understanding of physics and the Universe. 1240LLearn more at www.oerproject.com
2Sir Isaac Newton: Physics, Gravity, and Laws of MotionBy Cynthia Stokes BrownEarly life and educationIsaac Newton was born prematurely on January 4, 1643, in Lincolnshire, England. His father had died before his birth. When he was 3, his mother remarried and left him with his grandparents on a farm, while she moved to a village a mile and a half away from him. He grew up with few playmates, and amused himself by contemplating the world around him.His mother returned when Newton was 11 years old and sent him to King’s School. Rather than playing after school with the other boys, Newton spent his free time making wooden models, kites of various designs, sundials, even a water clock. When his mother, who was hardly literate, took him out of school at 15 to turn him into a farmer, the headmaster, who recognized where Newton’s talents lay, prevailed on her to let Newton return to school.Early discoveriesNewton attended Cambridge University from 1661 to 1665. The university temporarily closed soon after he got his degree because people in urban areas were dying from the plague. Newton retreated to his grandparents’ farm for two years, during which time he proved that “white” light was composed of all colors, and started to figure out calculus and universal gravitation—all before he was 24 years old.It was on his grandparents’ farm that Newton sat under the famous apple tree and watched one of its fruits fall to the ground. He wondered if the force that pulled the apple to the ground could extend out to the Moon and keep it in its orbit around Earth. Perhaps that force could extend into the Universe indefinitely.After the plague subsided, Newton returned to Cambridge to earn his master’s degree and become a professor of mathematics there. His lectures bored many of his students, but he continued his own thinking and experiments, undaunted. When his mother died, he inherited enough wealth to leave his teaching job and move to London, where he became the president of the Royal Society of London for Improving Natural Knowledge, the top organization of scientists in England.Laws of motion and gravityNewton’s most important book was written in Latin; its title was translated as Mathematical Principles of Natural Philosophy. It was published in 1687. The book proved to be one of the most influential works in the history of science. In its pages, Newton asserted the three Laws of Motion, elaborated Johannes Kepler’s Laws of Motion, and stated the Law of Universal Gravitation. The book is primarily a mathematical work, in which Newton developed and BornJanuary 4, 1643Lincolnshire, EnglandDiedMarch 31, 1727London, England
3Sir Isaac Newton: Physics, Gravity, and Laws of MotionBy Cynthia Stokes Brownapplied calculus, the mathematics of change, which allowed him to understand the motion of celestial bodies.To reach his conclusions, he also used accurate observations of planetary motion, which he made by designing and building a new kind of telescope, one that used mirrors to reflect, rather than lenses to refract, light.Illustration from The Mathematical Principles of Natural Philosophy by Isaac Newton. © CORBIS Newton’s three Laws of Motion1.Every body continues at rest or in motion in a straight line unless compelled to change by forces impressed upon it. Galileo Galilei first formulated this, and Newton recast it.2.Every change of motion is proportional to the force impressed and is made in the direction of the straight line in which that force is impressed. A planet would continue outward into space but is perfectly balanced by the Sun’s inward pull, which Newton termed “centripetal” force.3.To every action there is always opposed an equal reaction, or the mutual action of two bodies on each other is always equal and directed to contrary parts.Law Of Universal GravitationPutting these laws together, Newton was able to state the Law of Universal Gravitation: “Every particle of matter attracts every other particle with a force proportional to the product of the masses of the two particles and inversely proportional to the square of the distance between them.” Stated more simply, the gravitational attraction between two bodies decreases rapidly as the distance between them increases.
4Sir Isaac Newton: Physics, Gravity, and Laws of MotionBy Cynthia Stokes BrownThis calculation proved powerful because it presented the Universe as an endless void filled with small material bodies moving according to harmonious, rational principles. Newton understood gravity as a universal property of all bodies, its force dependent only on the amount of matter contained in each body. Everything, from apples to planets, obeys the same unchanging laws.By combining physics, mathematics, and astronomy, Newton made a giant leap in human understanding of Earth and the cosmos. Newton’s mathematical method for dealing with changing quantities is now called calculus. He did not publish his method, but solved problems using it. Later, the German scientist Gottfried Wilhelm von Leibniz also worked out calculus, and his notation proved easier to use. Newton accused Leibniz, in a nasty dispute, of stealing his ideas, but historians now believe that each invented calculus independently.Newton was made a knight by Queen Anne in 1705. At his death in 1727, he was buried in London’s Westminster Abbey. Shortly before he died, Newton remarked:I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the seashore and diverting myself in now and then finding a smoother pebble or prettier shell than ordinary, while the great ocean of truth lay all undiscovered before me.
5Sir Isaac Newton: Physics, Gravity, and Laws of MotionBy Cynthia Stokes Brown
6Sir Isaac Newton: Physics, Gravity, and Laws of MotionBy Cynthia Stokes BrownSourcesChristianson, Gale E. Isaac Newton. Oxford: Oxford University Press, 2005.Wills, John E. Jr. 1688: A Global History. New York and London: W. W. Norton, 2001.Cynthia Stokes BrownCynthia Stokes-Brown was an American educator-historian. Stokes Brown wrote Big History: From the Big Bang to the Present. Using the term big history, coined by David Christian at Macquarie University in Sydney, Australia, Stokes Brown told the whole story from the Big Bang to the present in simple, non-academic language to convey our common humanity and our connection to every other part of the natural world.Image credits This work is licensed under CC BY 4.0 except for the following: Cover image: Isaac Newton (1642-1727) english mathematician, physicist and astronomer, author of the theory of terrestrial universal attraction, here dispersing light with a glass prism, engraving colorized document. © Hulton Archive / Getty Images.Isaac Newton performing an experiment © Bettmann/CORBIS Illustration from The Mathematical Principles of Natural Philosophy by Isaac Newton © CORBIS Articles leveled by Newsela have been adjusted along several dimensions of text complexity including sentence structure, vocabulary and organization. The number followed by L indicates the Lexile measure of the article. For more information on Lexile measures and how they correspond to grade levels: www.lexile.com/educators/understanding-lexile-measures/To learn more about Newsela, visit www.newsela.comThe Lexile® Framework for ReadingThe Lexile® Framework for Reading evaluates reading ability and text complexity on the same developmental scale. Unlike other measurement systems, the Lexile Framework determines reading ability based on actual assessments, rather than generalized age or grade levels. Recognized as the standard for matching readers with texts, tens of millions of students worldwide receive a Lexile measure that helps them find targeted readings from the more than 100 million articles, books and websites that have been measured. Lexile measures connect learners of all ages with resources at the right level of challenge and monitors their progress toward state and national proficiency standards. More information about the Lexile® Framework can be found at www.Lexile.com.OER Project aims to empower teachers by offering free and fully supported history courses for middle- and high-school students. Your account is the key to accessing our standards-aligned courses that are designed with built-in supports like leveled readings, audio recordings of texts, video transcripts, and more. Offerings include a variety of materials, from full-year, standards-based courses to shorter course extensions, all of which build upon foundational historical thinking skills in preparation for AP, college, and beyond. To learn more about The OER Project, visit www.oerproject.com