Winward 1. Sir Isaac Newton. By Robert Winward. Physics Howard Demars

Transcription

1 Winward 1 Sir Isaac Newton By Robert Winward Physics 1010 Howard Demars

2 Winward 2 Introduction He was overly sensitive to criticism. His hair turned gray at thirty. He never married (Hewitt, 2011, p. 66). He held grudges. He laid the foundation for most of classical mechanics with his book, the Principia Mathematica Philosophiae Naturalis (Wikipedia, 2012). He was Isaac Newton. Centuries after his scientific discoveries were unsheathed they stand true and unchanged. His fellow Brits will forever remember him as one of the greatest scientists who ever lived (Hewitt, 2011, p.66). But what made him so great? Yes, his resume includes numerous inventions and discoveries, but what is their significance? In this paper you will learn about his two standout achievements: Newton s theory of universal gravitation, and his three laws of motion. Humble Beginnings Isaac Newton is undisputedly one of the greatest minds of all time. But if you knew much about the circumstances of his early life, you may find it surprising that a connection could be made between his early and latter years. Newton was born prematurely on Christmas Day, He barely survived the ordeal and was quite a frail child (Newton, 1993). Three months earlier his father had passed away. His mother remarried and fled to live with her new husband for several years, leaving the boy in the care of his grandmother (Wikipedia, 2012). Newton demonstrated no extraordinary signs of intelligence or creativity in his early years and was even taken out of school to help work on his mother s farm. He disliked farming, preferring to read books in his spare time. With encouragement from his uncle he returned to school.

3 Winward 3 A year later he was studying at the University of Cambridge. While there he developed the mathematic system of differential calculus which allowed him to analyze the curvature of shapes (Newton, 1993). The university closed for a time due to hype over the plague, and Newton returned to the farm. It was during this time that he performed his most important work that would forever carve his name in history. Universal Gravitation Isaac Newton did not discover that gravity existed. Rather, he discovered that gravity is not limited to this earth alone that is universal (Hewitt, 2011). And what set this train in motion was the falling of an apple from a tree. Upon seeing the sight, Newton thought to himself: Why should that apple always descend perpendicularly to the ground? Why should it not go sideways, or upwards? But constantly to the earths centre? Assuredly, the reason is that the earth draws it. (Hamblyn, 2011) Newton concluded that the earth had a drawing power upon the apple, and that the sum of that power was in the earths center (Hamblyn, 2011). This prompted him to think that if the earth pulls on the apple, then surely the apple must pull on the earth, relative to its mass. Newton concluded that all objects experience a gravitational force, and this force, acting between planets, is what keeps them in an orderly orbit. Newton also realized that gravity is affected by distance. He noted that the gravitational force that acts between objects is directly proportional to the product of

4 Winward 4 their masses and inversely proportional to the square of the distance between them. This is known as an inverse-square law (Hewitt, 2011, p. 154). For centuries, the causes of the rising and falling of ocean tides had remained a mystery. Newton now could offer an explanation. He saw that the moon follows an elliptical orbit around the earth; at different stages of its orbit it is closer to the earth that at other times. According to the inverse-square law, at these times of close proximity, the gravitational pull by the earth on the moon is greater and vice versa. As the moon pulls on the earth, it literally pulls the ocean closer to it. Obviously, this pull is greater on the side of the earth nearer to the moon. This theory accounted for the different levels of ocean tides. Newton s Laws of Motion Newton s first law of motion also known as the law of inertia is a refinement of Galileo s findings on inertia. Inertia is the property of an object to resist changes to its current state of motion. Newton s first law states that every object continues in a state of rest or uniform speed in a straight line unless an outside force is exerted on it (Hewitt, 2011, p. 23). For instance, think of a ball being thrown against a wall. Once thrown, the ball would continue in a straight line forever (disregarding gravity). However, it hits the wall (the outside force) and comes to an abrupt halt. The first man to see the relationship between acceleration, force, and mass was Newton (Hewitt, 2011, p. 56). He described this in his second law as a mathematical relationship: Acceleration ~ force/mass. As exerted force increases on an object, so will its acceleration. A more massive object will have a slower acceleration.

5 Winward 5 Newton s third law deals with force whenever one object exerts a force on a second object, the second object exerts an equal and opposite force against the first (Hewitt, 2011, p. 68). If you are bench pressing weights at the gym, the bar ball pushes downward against you with a force equal to you pushing upward against the bar bell. Similarily if you push against a wall the wall pushes back on you, even though it doesn t move. Newton s laws of motion are significant because they describe how things in the universe operate. Wherever you go in the universe these laws hold true. Everyday these laws are at work. Conclusion Alexander Pope once professed, God said, Let Newton be! and all was light! (Hewitt, 2011, p.18) Surely this is so. Newton clearly is one of the greatest and most influential scientists who ever lived (Burt, 2001, p.315). Where would we be now without his genius? Surely we wouldn t have made it to the moon, among other things. To this day his teachings remain in tack, because they are universal laws, laws that transcend time without change. And they are at work all around us. No matter how much you wish for it, that T.V. remote control will not pick itself up off the coffee table and place itself in your hands. Only you the outside force can get it to move. Next time you re driving, know that the road is pushing upward on the tires of your car, just as they equally press down on the road.

6 Winward 6 Works Cited Burt, Daniel S. (2001). The biography book: a reader's guide to nonfiction, fictional, and film biographies of more than 500 of the most fascinating individuals of all time. Greenwood Publishing Group. p ISBN Hamblyn, R. (2011). The art of science. (Newtonian Apples: William Stukeley ed.). Pan Micmillan. Hewitt, P. (2011). Conceptual physics. (11th ed., pp ). Pearson. Isaac newton. In Wikipedia. Retrieved April 16, 2012 from Newton, Isaac. (1993). Old Worlds to New.