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## Sir Issac Newton

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**Sir Issac Newton**By Cadet Co____**Biography**• Isaac Newton was born on the 25th December 1642 in Woolsthorpe, Lincolnshire. His father was a farmer but he died three months before Newton was born. His mother remarried and Newton spent his childhood with his grandmother. At school he showed great skill in making model kites, sundials and windmills. In 1665 when he was 18 he went to study mathematics at Cambridge University. He continued his studies at home when the University closed because of the plague.**His Scholarship**• When the University of Cambridge reopened after the plague in 1667, Newton put himself forward as a candidate for a fellowship. In October he was elected to a minor fellowship at Trinity College but, after being awarded his Master's Degree, he was elected to a major fellowship in July 1668 which allowed him to dine at the Fellows' Table.**His inventions**Newton made the first reflecting telescope in 1668. - In 1670 Newton worked more on chemistry and alchemy than on optics and mathematics. It is said that Newton wondered why objects fell to earth when he was sitting in a garden and saw an apple drop in front of him. Newton thought back to the subject which he was thinking about in 1665-66. This was "Why things move as they do." He proposed his three laws of motion. - Newton thought that earth's gravitational force extended right to the moon. He was the first person to give an explanation of the tides. - Newton invented the Calculus branch of mathematics around 1669. He did not publish his ideas until around 1704, 35 years later**Mechanics and gravitation**According to the well-known story, it was on seeing an apple fall in his orchard at some time during 1665 or 1666 that Newton conceived that the same force governed the motion of the Moon and the apple. He calculated the force needed to hold the Moon in its orbit, as compared with the force pulling an object to the ground. He also calculated the centripetal force needed to hold a stone in a sling, and the relation between the length of a pendulum and the time of its swing. These early explorations were not soon exploited by Newton, though he studied astronomy and the problems of planetary motion.**Newton's First Law of Motion:**Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.**Newton's Second Law of Motion:**The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector.**Newton's Third Law of Motion:**For every action there is an equal and opposite reaction.