who changed Newton's second law into F=ma and why?
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The rate of change of momentum of a body is proportional to the resultant force acting on the body and is in the same direction.\n\nIn an exact original 1792 translation (from Latin) Newton's Second Law of Motion reads:\n\nLAW II: The alteration of motion is ever proportional to the motive force impressed; and is made in the direction of the right line in which that force is impressed. — If a force generates a motion, a double force will generate double the motion, a triple force triple the motion, whether that force be impressed altogether and at once, or gradually and successively. And this motion (being always directed the same way with the generating force), if the body moved before, is added to or subtracted from the former motion, according as they directly conspire with or are directly contrary to each other; or obliquely joined, when they are oblique, so as to produce a new motion compounded from the determination of both.\n\nNewton here is basically saying that the rate of change in the momentum of an object is directly proportional to the amount of force exerted upon the object. He also states that the change in direction of momentum is determined by the angle from which the force is applied.\n\nHowever, it must be remembered that for Newton, mass was constant and independent of velocity. To take "motion" (motu) as meaning momentum gives a false impression of what Newton believed. Since he took mass as constant (part of the constant of proportionality) it can, in modern notation, be taken to the left of the derivative as . If  is dependent on velocity (and thus indirectly upon time) as we would now hold, then  has to be included in the derivative, giving  or .\n\nUsing momentum in the terminology (which would never have occurred to Newton) is a latter-day revision of the law to bring it into correspondence with special relativity.\n\nInterestingly, Newton is restating in his further explanation another prior idea of Galileo, what we call today the Galilean transformation or the addition of velocities.\n\nAn interesting fact when studying Newton's Laws of Motion from the Principia is that Newton himself does not explicitly write formulae for his laws which was common in scientific writings of that time period. In fact, it is today commonly added when stating Newton's second law that Newton has said, "and inversely proportional to the mass of the object." This however is not found in Newton's second law as directly translated above. In fact, the idea of mass is not introduced until the third law.\n\nIn mathematical terms, the differential equation can be written as:\n\n \nwhere  is force,  is mass,  is velocity,  is time and  is the constant of proportionality. The product of the mass and velocity is the momentum of the object.\n\nIf mass of an object in question is known to be constant and using the definition of acceleration, this differential equation can be rewritten as:\n\n \nwhere  is the acceleration.\n\nUsing only SI Units for the definition of Newton, the constant of proportionality is unity (1). Hence:\n\n \nHowever, it has been a common convention to describe Newton's second law in the mathematical formula  where  is Force,  is acceleration and  is mass. This is actually a combination of laws two and three of Newton expressed in a very useful form. This formula in this form did not even begin to be used until the 18th century, after Newton's death, but it is implicit in his laws.
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Sir Isaac Newton, PRS, \n\n\n(4 January 1643 – 31 March 1727) [OS: 25 December 1642 – 20 March 1727] was an English physicist, mathematician, astronomer, alchemist, inventor, and natural philosopher who is generally regarded as one of the most influential scientists in history.\n\nNewton wrote the Philosophiae Naturalis Principia Mathematica wherein he described universal gravitation and the three laws of motion, laying the groundwork for classical mechanics. By deriving Kepler's laws of planetary motion from this system, he was the first to show that the motion of bodies on Earth and of celestial bodies are governed by the same set of natural laws. The unifying and deterministic power of his laws was integral to the scientific revolution and the advancement of heliocentrism.\n\nAmong other scientific discoveries, Newton realized that the spectrum of colours observed when white light passes through a prism is inherent in the white light and not added by the prism (as Roger Bacon had claimed in the 13th century), and notably argued that light is composed of particles. He also developed a law of cooling, describing the rate of cooling of objects when exposed to air. He enunciated the principles of conservation of momentum and angular momentum. Finally, he studied the speed of sound in air, and voiced a theory of the origin of stars.\n\nAmong Westerners, Newton played a major role in the history of calculus, sharing credit with Gottfried Leibniz. He also made contributions to other areas of mathematics, having derived the binomial theorem in its entirety. The mathematician and mathematical physicist Joseph Louis Lagrange (1736–1813), said that "Newton was the greatest genius that ever existed and the most fortunate, for we cannot find more than once a system of the world to establish
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alright, well just convert the mN into N and divide by gravity... \nso we multiply be the conversion factor getting .00000671N. now F=ma=mg so m=F/g(mass equals Force divided by gravity)  so .00000671/9.8= 6.85 x 10^-7 kg
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according to newton's second law, F=ma\nso, initially, let the force be F1, mass be m1 and the acceleration be a1\nthe final force is F2, mass is m2 and the accleration is a2\nF1=m1a1 and F2=m2a2\nas the force is decreased by a factor of 3.7, F2=F1/3.7\nand since the mass is decreased by a factor of 2.6, m2=m1/2.6\nF1/F2=m1a1/m2a2\nso, 3.7=2.6*a1/a2\nbut a1=8m/s^2\nso, a2=2.6*8/3.7\nso, a2=5.62m/s^2\nthis is the new acceleration
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With zero net force there are so many examples. Book resting on the table. Vehicle moving with constant velocity. Rain drops falling with terminal velocity. Object floating on water. Mass hanging from a spring balance. \n\nBut the example of a known total force F, acting on mass m and producing accelerartion a = F/m in the mass m is difficult to give. This is so because of two reasons. Firstly because rarely only wellknown forces act on an object, most of the time not so                                   wellknown forces such as that of reaction tension and friction also act on the objcet. Secondly, strictly speaking there exists no definition of mass other than Newton's second law. Newton's Second law define both force and mass.  In this sense this is not a law but a definition of some sort. on the basis of which you can derive certain results of experiment which can be verified.
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* 1 Newton's first law: law of inertia\n* 2 Newton's second law: An applied force is equal     to the rate of change of momentum.\n* 3 Newton's third law: law of reciprocal actions\n\nClick the link and read all about it.
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It is reputed to have been Lord Kelvin.  The Michelson-Morley experiment (to find the true reference frame of the universe - the failure of which led to Einstein's discovery of special relativity) and the solution to the blackbody radiation equation (which led to the "ultraviolet catastrophe" and Planck's discovery of quantum mechanics) was all that was left, other than extending the constants to additional decimal places.\n\nHowever, Feynman claims this is more myth than fact.
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Hey babygurlgonnaloveonu you have asked what is totally QUESTION NUMBER ONE in physics. It's an exciting question which many teachers secretly don't understand and so their students get this hazy idea and kind of go thru the motions. \n\nWow, it is so basic, that it took a super-genius, I mean way smarter than Einstein, to figure it out. A good old farm boy, astrologer, magician & alchemist, religious fanatic, mathematician and all around kook. Yep. Sir Isaac Newton. You gotta wonder what kind of parents would name their kid "Sir"\n\nWell we all know what a force is, it is a sort of push or pull -- think of it as something that changes or *tries to change* the motion of stuff.\n\nNewton first figured out that if you leave a thing alone, or if the pushes and pulls on it cancel out, then it will sit there like a lump. Like those drivers wearing hats, and like sit there after the light has already turned green two minutes ago. \n\nOr else a thing  will keep moving in the same straight line direction and speed  like those drivers wearing hats who go 40 mph on the expressway with their turn signal blinking on and on. This is known as "THE HAT LAW".\n\nAll was well until he noticed that things move faster in an amount equal to how much you bully them or push them around. Twice the force, twice the fasterness and fasterness (also known as acceleration). This is called the "YOU BIG BULLY LAW".\n\nThen he discovered a fly in the ointment. His HAT and BULLY laws didn't really explain all that much. Something was gumming up this beautiful theory. We call it MASS and it is still an unknown mystery as to what it really is. So we vaguely call it the amount of stuff or matter in a thing. \n\nSo he found out that for a certain force the faster-isity (acceleration) is cut in half if you double the mass. The bully has to push twice as hard to fasterize two little kids. So he was like "I'll just add that in, and all will be cool". The "YOU BIG BULLY LAW" and "THE HAT LAW" totally did it all. Wa ta da babee!\n\nBut then Newton had a road accident. He was gunning his Harley over London bridge at like 250 when a bug  hit him in the mouth and knocked out one of his wooden teeth. He was all "Why am I so in pain?". And the bug as it squooshed said "Help! I'm a bug!"\n\nSo spitting out the splinters of his wooden tooth and the splattered bug, he had this revelation. He realized that because he was moving so fast, and the  bug slowed down so fast, that even a eentsy mass like a bug was like taking a hammer to his tooth. \n\nHe noticed that the force was equal to the mass of the bug times the speed of impact all happening in a brief moment. Since Newton spoke Latin (he  was the love child of Joe Newton and an Italian governess) he wrote "Fastus buggus ina momentum hurtus like crazy." Today we call this "momentum". It is just "mass times speed" or "force times a small moment of time". \n\nAnd he realized that the bug smashed up his tooth, but also that the bug was squashed (like a bug) because they were trading the EXACT same amount of momentum. The force on the tooth by the bug in the moment of time was PRECISELY equal to the  smacko-ing the tooth used to stop the bug dead. \n\nHe said "Hey, like he broke my tooth, but I killed him soooo dead!" He did the math and found that the force of the bug on the tooth was equal to the force of the tooth on the bug! \n\nNo way did the two equal forces cancel, after all, his tooth was hammered to splinters, and the bug was flattened. They were equal and opposite, but since one was on the tooth, and the other force was on the bug they did serious damage! Today we call this the "HELP I'M A BUG" law.\n\nNow our man 'Zack was all set. He wrote down his three laws:\n\nTHE HAT LAW (beeep! beeep! Move it Hat Guy!)\nTHE YOU BIG BULLY LAW (betcha can't kno
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sir isaac newton. the man who "discovered" the law of gravity.
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L = 8pi G rho/c^4 is the definition of the cosmo constant L (1/m^2); where c = light speed and rho is the energy density of the known universe in a vacuum.\n\nF = GmM/r^2 is the equation for the attraction force F between two masses m and M, r distance apart.\n\nL was created by Einstein to make his equations come out right.  By that, he meant the universe should be spherical (not flat or saddle shaped).  His original results showed a flat universe, and he just "knew" that was wrong; so on came L to fix the shape problem.\n\nF was the result of experiments by Newton.  Through observation, he found that the attractive force between two bodies was proportional to the inverse square of the distance between them and to the product of the magnitudes of the two masses.  That is, F varies as (~) (mV/r^2).  \n\nWhenever there is a proportionality, as in F ~ mM/r^2, there has to be a constant of proportionality.  In this case Newton called it G; so that F ~ mM/r^2 becomes F = GmM/r^2 when the constant is inserted.\n\nThe G in both equations is the same constant.  But Sir Newton came upon it long before Einstein found it could be used in his equations and the calculation of L.  So there is no way that Newton (1642-1727) could know about Einstein's (1879-1955) use of it much later.
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E=Mc^2 is not newtons 2nd law of motion\n\nEnergy = mass in kg * the speed of light squared which is in m/s\nThat is the full equation,it is by no means a proof but it is the equation\nNewtons 2nd law of motion is mass * acceleration,acceleration has units of m/s^2\n\nLight does not accelerate\n\nE= mc^2 is used to find how much erergy is required to create new mass,it is used a lot in particle physics
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Newton' and Einstein's on relativity
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Force - Newtons\nMass - Kilograms\nAcceleration - metres per second
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Sir Isaac Newton developed the universal law of gravitation.  This law was developed as an inverse square law (1/(r squared) where r is the distance between the two objects.). This law states that all masses are attracted to each other no matter how far away from each other they are.  The key to this law is that the force at which they pull at each other is not only inversely proportional the square of their distance apart but also dependent on their mass.  The equation is as follows:  F=G*((m1*m2)/(r squared) where F is the force created between them, m1 and m2 are the masses in kg of the objects and G is the universal gravitation constant which is 6.642 x10(-11) N M(2)kg(-2) (these last letters are the units it is in.)\nThe Force at which any object on earth has is simply the mass of that object times the acceleration at the surface which is 9.81 m/s(2) this force is the same as if you put the mass of the earth times that objects mass times the gravitational consant then divided by the square of the distance to the center of the earth.\n     As far as I am aware all field forces are inverse square laws which basically means that the closer an objects gets to another the attraction between then increases as the square of the previous force.  The closer they are together the stronger the force.\n     The string theory was devised to explain multiple dimensions and as a way to explain how subatomic particles can seem to be in more than one place at once.  It consists of a tube (string) that has a very small diameter but is infinitely long.  In this theory there are also an infinite number of these strings floating all over invisibly each containg multiple galaxies.  Hope this helps.
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convert to Newtons from mN, then divide by gravity because F=mg. so you get .00000780/9.8
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Newton's second law:\nFirstly, this law states that if you do place a force on an object, it will accelerate, i.e., change its velocity, and it will change its velocity in the direction of the force.\nSecondly, this acceleration is directly proportional to the force. For example, if you are pushing on an object, causing it to accelerate, and then you push, say, three times harder, the acceleration will be three times greater.\nThirdly, this acceleration is inversely proportional to the mass of the object. For example, if you are pushing equally on two objects, and one of the objects has five times more mass than the other, it will accelerate at one fifth the acceleration of the other.
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I've alread answered two of your questiions in my last answer....\n\nIn this one, the guys above are correct - however, I'd try working it out for myself if I was you. Your tutor will soon realise something is wrong if you are giving answers to a subject you don't understand. Read the chapter, ask you teacher if you need more help. Learn Newtonian mechanics for yourself.