Dynamics the branch of mechanics concernedwith the motion of bodies under the action of forces.The Newtons’s laws of themotion are the action of dynamics.These laws provide an example of the width ofprincipals under nature functions.The Newton’s laws were monumental work thathas made him the person who he was.This transition was characterized by arevolutionary change in the way people thought about physical universe.
Newton started to explain phenomena through theuniverse. What lay within was to apply everywhere, and to every process. Thetrajectory taken by a cannon ball was to be governed by the same laws whichgoverned the orbits of the other planets. As the start of his work, he stateshis definitions of mass, momentum, inertia and forces, both through contact andat a fixed distance. He states his three laws:First Law Everybody in it’s state of the rest, or of uniform motion in a rightline,it be completed to change that state by forces impressed in it thereon.Second Law The alteration of motion is to the motive force impressed; and is madein the direction of the right line in which that force is impressed.Third Law Every action there is always opposed an equal reaction: or the mutualactions of two bodies upon each other are always equal, and directed tocontrary parts.
It is broadly divided intothree books, each of this books which alone would eclipse almost any other.Books One and Two are titled Of the Motion of Bodies, being split into two analyses.The third book of Isaac Newton is titled The System of the World.1-The first book organisedand systematised principles, some of which were at least dimly understoodbefore, but these principles had never been organised together into a system ofanalysis for application .2-The second book sets outto explain motion on Earth, where motion does not occur in: the details ofmotion in resisting media. It is here that Newton departs from his program ofdeducing physical behaviour based on his laws: he finds but little use for them3- The third book setforth his solutions to problems in celestial dynamics, with great success.Kepler’s Laws of Planetary Motion had resulted from Newton’s own, and heperformed exhaustive analyses of the Solar System.
GalileoGalileo Galilei (1564–1642), these descriptions of motion: hewas the first of the modern dynamicists. He was in the workings of both the Parisian and Mertonianschools. From these, he started into the still poorly understood field ofkinetics. To move forward, he was successful of the ancient sciences:Archimedes’ hydrostatics. He took those principles as inspiration to examinethe motion of a falling object.
He utilised no mixed–body theory of matter.Instead, he treated the bodies, and the media through which they traveled, interms of their densities . Archimedes’ propositions explain the forces ofbuoyancy in equilibrium: they detail where an object will rest in a body ofwater. Galileo extended these principles from static into dynamic concepts.Archimedes explained the behaviour of bodies andtheir natural positions of rest. Galileo took this notion and applied it tobodies in motion. His monumental postulation was that buoyancy, in addition todetermining a body’s position of rest, furthermore determines how fast a bodywill reach that position of rest. He used this force of buoyancy to try toexplain why objects fell at the speed they did.
It is wrong to say that hedevised a dynamical law based on static principles. His theorems are ageneralisation of Archimedes’ static principles, which are then derivable fromGalileo’s: the converse is untrue. These notions were not new. Instead of usinga ratio of weight to resistance in order to explain motion, Galileo describedit as a natural motion from which was subtracted the effect of the medium.
Instead of having velocity determined by the ratio of a body’s weight to themedium’s resistance, it was to be determined by a natural value minus some partdue to the resistance of the medium. The approach, ingenious though it was, ledto no hoped for grand principle. The comparison between Galileo and Avempace iscommonly drawn, as Avempace had postulated the same kind of thing: discardingthe Aristotelian ratio. Galileo was certainly aware of Avempace’s work, throughwhat Averr¨oes wrote of it. It is unfair to say that Avempace was theoriginator of this sort of analysis, as it predates him by hundreds of years.
This theory again goesback to John Philoponus, who was also well known to Galileo. Additionally,Avempace did not postulate Galileo’s explanations for the causes of motion.