Isaac newton (Isaac Newton1642.12.25 ——1727.3.20) is a British physicist, mathematician, astronomer and natural philosopher. The most famous mathematician, scientist and philosopher in Britain at that time, and also a brief introduction of the alchemist. The law of gravitation and Newton's law of motion put forward by him in Mathematical Principles of Natural Philosophy published on July 5, 1687 are the cornerstones of classical mechanics. Newton and Leibniz also independently invented calculus. He always left more than 500,000 words of alchemy manuscripts and 6,543,800 words of theology manuscripts. Young Newton1643 65438+1October 4th, Newton was born in a farmer's family in Walsop, Lincolnshire, England. Newton was a premature baby, weighing only three pounds at birth. The midwife and his relatives are worried about whether he will survive. No one expected that this seemingly insignificant little thing would become a giant of science and live to be 85 years old. Three months before Newton was born, his father died. When he was two years old, his mother remarried to a priest and left Newton to his grandmother. 1 1 years old, my mother's step hubband passed away, and my mother returned to Newton with a son and two daughters born with step hubband. Newton was taciturn and stubborn since childhood, which may come from his family situation. From about the age of five, Newton was sent to public schools. Newton was not a child prodigy when he was a teenager. He has average qualifications and average grades, but he likes reading books, reading books that introduce various simple mechanical model making methods, and being inspired by them, he makes some strange gadgets by himself, such as windmills, wooden clocks, folding lanterns and so on. Legend has it that young Newton made a model of the mill after thoroughly understanding the mechanical principle of the windmill. He tied the mouse to a treadmill with wheels, and then put a corn in front of the wheel, just out of the mouse's reach. The mouse wants to eat corn, so it keeps running, so the wheel keeps turning; Once again, when he was flying a kite, he hung a small lamp on the rope. In the evening, the villagers were surprised to find that a comet appeared. He also made a small water clock. Every morning, the water bell will automatically drop water on his face to wake him up. He also likes painting and carving, especially carving sundials. His sundial was placed in the corner of his house and everywhere on the windowsill to observe the movement of the shadow. Newton entered Grantham Middle School not far from home at the age of 12. Newton's mother had hoped that he would become a farmer, but Newton himself had no intention of doing so and loved reading. As he grew older, Newton became more and more fond of reading, meditating and doing small scientific experiments. When he was studying in Grantham Middle School, he lived in a pharmacist's house, which influenced him by chemical experiments. Newton's contribution to achievement mechanics Newton made an in-depth study on the basis of the work of Galileo and others, and summed up three basic laws of object motion (Newton's three laws): ① When any object is not subjected to external force or the resultant force of external force is zero, the original motion state remains unchanged, that is, the original motion continues to be static and the original motion continues to move in a straight line at a constant speed. ② Under the action of external force, the motion state of any object changes, and the rate of change of its momentum with time is directly proportional to the resultant force. Generally speaking, it can be expressed as: the acceleration of an object is directly proportional to the acting force and inversely proportional to the mass of the object, and the direction of acceleration is consistent with the direction of the acting force. (3) When object A gives object B a force, object B must give object A a reaction force at the same time. Force and reaction force are equal in magnitude and opposite in direction, on the same straight line. These three very simple laws of motion have laid a solid foundation for mechanics and exerted great influence on the development of other disciplines. Galileo once put forward the content of the first law, and then R Descartes made a formal improvement, and Galileo also informally mentioned the content of the second law. The content of the third law was obtained by Newton after summing up the achievements of C Lane, J Wallis and C Huygens. Newton was the discoverer of the law of universal gravitation. He began to think about this problem in 1665 ~ 1666. 1679, R. Hook wrote to him that gravity should be inversely proportional to the square of the distance, and the trajectory of the projectile at the height of the earth is elliptical. Suppose there is a crack in the earth, the projectile will return to its original place, instead of the spiral line towards the center of the earth as Newton imagined. Newton didn't reply, but adopted Hooke's opinion. Based on Kepler's laws of planetary motion and other people's research results, he mathematically deduced the law of universal gravitation. Newton unified the mechanics of objects on the earth and celestial mechanics into a basic mechanical system and established a classical mechanical theoretical system. It correctly reflects the macro motion law of macro objects at low speed and realizes the first great unity of natural science. This is a leap in human understanding of nature. Newton pointed out that the viscous resistance of fluid is proportional to the shear rate. He said: the resistance caused by the lack of lubricity between fluid parts, if everything else is the same, is proportional to the separation speed between fluid parts. At present, fluids that conform to this law are called Newtonian fluids, including the most common water and air, and those that do not conform to this law are called non-Newtonian fluids. When Newton gave the resistance of a flat plate in the airflow, he adopted a particle model for the gas, and concluded that the resistance was proportional to the sine square of the angle of attack. This conclusion is generally incorrect, but because of Newton's authoritative position, later generations have long regarded it as a creed. In the 20th century, T Carmen said humorously when summing up the development of aerodynamics that Newton made the plane go to heaven a century later. Regarding the speed of sound, Newton correctly pointed out that the speed of sound is directly proportional to the square root of atmospheric pressure and inversely proportional to the square root of density. However, because he regards sound propagation as an isothermal process, the result is inconsistent with reality. Later, P.-S. Laplace revised Newton's formula of sound speed from the perspective of adiabatic process.