* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Newton`s Laws of Motion
N-body problem wikipedia , lookup
Inertial frame of reference wikipedia , lookup
Hooke's law wikipedia , lookup
Coriolis force wikipedia , lookup
Hunting oscillation wikipedia , lookup
Jerk (physics) wikipedia , lookup
Center of mass wikipedia , lookup
Relativistic mechanics wikipedia , lookup
Fictitious force wikipedia , lookup
Classical mechanics wikipedia , lookup
Seismometer wikipedia , lookup
Modified Newtonian dynamics wikipedia , lookup
Centrifugal force wikipedia , lookup
Mass versus weight wikipedia , lookup
Newton's theorem of revolving orbits wikipedia , lookup
Equations of motion wikipedia , lookup
Rigid body dynamics wikipedia , lookup
Centripetal force wikipedia , lookup
Summary/Review Notes related to the Ideas called Isaac Newton’s “Laws of Motion” Understanding Newton’s “Laws of Motion” is not an easy matter. This understanding often begins when a student wrestles with Newton’s idea called Momentum. An object’s Momentum is its “total quantity of motion”. Momentum is the product of an object’s mass and its velocity. Expressed mathematically this is: ρ=m∙v Whenever the word “motion” appears in a translation of Newton’s writings, it is important to remember this definition of Momentum. Common summary of the ideas: First Law of Motion: Objects in motion remain in motion unless acted upon by an outside force; also, objects at rest remain at rest unless acted upon by an outside force. Second Law of Motion: Acceleration is proportional to the causative force & inversely proportional to the mass upon which the force acts. (a = F ÷ m, which is often written as F = m • a ) The greater the net force impressed, the faster an object changes. Third Law of Motion: To every action there is an equal and opposite reaction. Nothing can touch without being touched. ___________________________________________________________________ Some more detailed thoughts about the Ideas: Newton's First Law of Motion Every body will persist in its state of rest or its state of uniform motion in a straight line unless that state is changed by forces impressed upon it. This is often called the Law of Inertia. (Inertia is a property of all matter…..matter resists having its state of motion changed. Mass is the measurement of an object’s resistance to change of motion.) Stated in another way: The momentum of an object will be constant until an outside force increases or decreases that momentum. Newton's Second Law of Motion When an object accelerates, the size of that acceleration is directly proportional to the force applied, and inversely proportional to the mass of the body. Further, the acceleration will take place in the same direction as the applied force. Expressed mathematically this is: a=F÷m Alternatively, it can be written as F = ma (In Words: Force is the mass times the acceleration) In both cases: F = force applied to a body (e.g., in Newtons) m = mass of the body (e.g., in kilograms) a = acceleration the body experiences in response to the force applied (e.g., in m ) sec 2 Stated in another way: The rate at which the momentum of an object changes is proportional to the net force acting on the object, and the change will be in the direction of that net force. Expressed mathematically this is: F = Δρ ÷ Δt Force, Mass, & Acceleration The second law has two parts: A) Quantifies the idea of a force in terms of its effects on a massive body. • • Forces produce accelerations. The more mass a body has, the less it will be accelerated by a given force. B) Forces and accelerations have a direction (they are both vectors): • Accelerations happen in the same direction as the applied forces. Newton's Third Law of Motion The mutual actions of two objects upon one another are always equal in amount and directed towards contrary parts of the world. Forces exist in pairs….. “simultaneous” and “mutual” in effect, “equal” in magnitude, “opposite” in direction. The third law brings together the first and second laws, which deal with single bodies. The third law makes clear that “forces” are actually interactions between bodies. Force is not what one body does…….force is really the way in which two bodies interact with one another. • • If an apple is placed on a table in our room, the apple pushes down on the table with a force equal to its mass times the acceleration due to gravity. If the apple sits stationary (unmoving) while pushing down on the table, the table must be exerting a force on the apple equal in magnitude and opposite in direction. For students who would like a look at the original form of the ideas, here they are as Newton expressed them in Latin which was the scholarly language of his time. AXIOMATA, SIVE LEGES MOTUS Lex I Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi quatenus illud a viribus impressis cogitur statum suum mutare. Lex II Mutationem motus proportionalem esse vi motrici impressae, & fieri secumdum lineam rectam qua vis illa imprimatur. Lex III Actioni contrariam simper & aequalem esse reactionem: sive corporum duorum actions in se mutuo simper esse aequales & partes contrarias dirigi. from Philosophiae Naturalis Principia Mathematica (authored by Isaac Newton; publ. 1687) (The Mathematical Principals of Natural Philosophy)