Newton’s Laws of Motion

Elevator down

"If I see further than others, 
it is because I stand on the shoulders of giants."
Isaac Newton

Isaac Newton
 Isaac Newton achieved his greatness in the annals of science as much for validating and organizing the work of others as for the new thinking he brought to the physics landscape. The story of how a set of rules we call Newton's laws of motion came to exist in their present form is interesting as much for revealing some of the quirks and biases that Newton held as it relates the laws themselves. Newton was born on Christmas day in 1642, the same year that Galileo died. His father had died before he was born and when his mother remarried, Isaac went to live with grandparents. We surmise that the loneliness he encountered in life had its foundation in a childhood devoid of affection from parents. He enrolled at Trinity College, Cambridge University, and joined the faculty there upon graduation.
When the bubonic plague swept through Europe in 1665-66, the University shut down and all faculty and students were sent home. It was here in his garden at Woolsthorpe that the apocryphal story of an apple falling from a tree caused him to speculate the the force required to cause this event may be the same force that holds the moon in place around the Earth. Despite the fact he had uncovered a major piece of mechanics, he was content to hold his ideas for himself; he did not publish. It was not until eighteen years later in 1684, when approached by Edmund Halley, that he revisited these ideas. Halley was at odds with Robert Hooke, a powerful figure in science circles in England and,not-so-coincidentally, the object of a bitter professional rivalry with Newton. Halley asked Newton about the force necessary to keep one object in orbit around the other. Newton suggested that the relationship followed an inverse square rule; he agreed to send the proof to Halley. The proof took two years to write and manifests itself as Philosophiae Naturalis Principia Mathematica, the first real physics book. Newton was instantly recognized for the genius that he was and eclipsed all of the other scientists of his time.  By themselves, Newton's laws seem very innocuous; three short statements, one of which is a very short equation. The laws look pretty simple. They are in fact very powerful statements, the fallout from which has direct bearing on you every time you move. The analysis of simple situation to determine how Newton's laws describe how nature behaves can often be very trying. We will approach this analysis slowly and systematically to ensure that you understand as we progress.

Edmund Halley

Robert Hooke

Click here to go to
1. The laws explained  4.Astronomy Retrospective
2. The Laws Applied 
(friction, inclined planes, et al.)
 5. Universal gravitation 
3. Uniform circular motion  6.Pressure, buoyancy,
& other force phenomena

 7_ Simple Harmonic Motiom

 This page last edited 01/23/09

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