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Why do we not refer to Newton's universal law of gravitation as Newton's 4th law. Why are his first three packaged together: inertial mass, f=ma, action/reaction, while his 4th, f=Gmm/r^2 stands alone?
Newton's 4th Law: Unpacking Gravitational Force
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In summary, Newton's universal law of gravitation is not considered his 4th law of motion because it is not directly related to the concept of motion. His first three laws, which describe motion in Newtonian mechanics, are grouped together as "Newton's three laws of motion." Newton himself presented these laws as axioms or fundamental principles, while the law of universal gravitation was derived from them through mathematical reasoning. Therefore, it is not considered a fourth law of motion but rather an important consequence of the first three laws.
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Fightfish
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Because these three laws are the fundamental basis for describing motion in Newtonian mechanics. They are collectively referred to as "Newton's three laws of motion". Obviously his law of universal gravitation doesn't constitute a "4th law of motion", and so there you have it
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AlephZero
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Because that is what Newton did.
He gave the first three numbered "Axioms, or Laws of Motion" in the preface to "Principia".
Most of Book I (about 200 pages of rather dense math, in my translation) is a derivation of the "unversal law of gravitation" and its consequences, starting from the laws of motion and the observational evidence of Kepler's laws of planetary motion, which state what happens to orbits in the solar system, but not why it happens. Newton treats this as an exercise in math, not a "law": if Kepler's "laws" are true, then universal gravitation follows from them.
He gave the first three numbered "Axioms, or Laws of Motion" in the preface to "Principia".
Most of Book I (about 200 pages of rather dense math, in my translation) is a derivation of the "unversal law of gravitation" and its consequences, starting from the laws of motion and the observational evidence of Kepler's laws of planetary motion, which state what happens to orbits in the solar system, but not why it happens. Newton treats this as an exercise in math, not a "law": if Kepler's "laws" are true, then universal gravitation follows from them.
FAQ: Newton's 4th Law: Unpacking Gravitational Force
What is Newton's 4th Law: Unpacking Gravitational Force?
Newton's 4th Law is a theoretical concept proposed by physicist Isaac Newton which states that the force of gravity can be broken down into smaller components, allowing for a better understanding and explanation of the phenomenon.
How does Newton's 4th Law differ from the other 3 Laws of Motion?
Unlike the other three laws, which focus on the motion of objects and the forces acting upon them, Newton's 4th Law deals specifically with the force of gravity and how it can be analyzed and understood in more detail.
What is the purpose of Newton's 4th Law?
The purpose of Newton's 4th Law is to provide a more comprehensive understanding of the force of gravity and how it operates in the universe, allowing for more accurate predictions and explanations of physical phenomena.
How is Newton's 4th Law relevant in everyday life?
Newton's 4th Law is relevant in everyday life because the force of gravity affects everything around us. From the movement of planets and stars to the way objects fall to the ground, understanding this law helps us make sense of the world we live in.
Is there any evidence to support Newton's 4th Law?
While Newton's 4th Law is still a theoretical concept and has not been fully proven, there is evidence to support its validity. For example, the law accurately explains the motion of planets and other celestial bodies in our solar system, as well as the gravitational interactions between objects on Earth.