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The newton’s three laws of motion

Brian Hwang. The newton’s three laws of motion. Newton’s Three Laws of Motion. The laws explain the relationship between the net force on a body and its motion .

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The newton’s three laws of motion

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  1. Brian Hwang The newton’s three laws of motion

  2. Newton’s Three Laws of Motion • The laws explain the relationship between the net force on a body and its motion. • The three laws were presented through Issac Newton's book PhilosophiæNaturalis Principia Mathematica(Mathematical Principle of Natural Philosophy)

  3. PhilosophiæNaturalis Principia Mathematica • The book was released on July 5th, 1687. • It is considered to be one of the most important scientific books. • It states Newton's laws of motion, Newton's law of universal gravitation, and a derivation of Kepler's law of planetary motion.

  4. F=ma This simple equation can be used to explain the first two Newton’s laws of motion.

  5. The First Law of Motion “Lex I: Corpus omneperseverare in statusuoquiescendivelmovendiuniformiter in directum, nisi quatenus a viribusimpressiscogiturstatumillummutare.” • It states that every object continues in a state of rest or in a state of motion at a constant speed along a straight line, unless it is compelled to change that state by a net external force. • A state of rest can be merely considered as a state of motion at a constant speed of zero along a straight line.

  6. The First Law of Motion (Cont.) • The first law is also known as the Law of Inertia. *Inertia – resistance to acceleration. (Inertia is proportional to mass) • F= ma -> a = F/m This demonstrates that the acceleration is directly proportional to the net force.

  7. The Second Law of Motion “Lex II: Mutationemmotusproportionalemesse vi motriciimpressae, et fierisecundumlineamrectam qua visillaimprimitur.” • The second law is the most important law of the three laws. • It states that When a net force (ΣF) acts on an object of mass (m), the acceleration (a) that results is directly proportional to the net force and has a magnitude that is inversely proportional to the mass. • The direction of the acceleration is the same as the direction of the force. • This law states the formula F=ma

  8. Example of the Second Law • For example, if one flicks a small pebble, the pebble will bounce away. That means the pebble accelerated at a high rate. • However, if one flicks a huge, heavy rock, it will hardly move away. That means the rock accelerated at an insignificantly slight rate.

  9. SI Unit Newton • From the second law, the unit of force N (Newton) can be derived. • F = m*a = kg * m/s2 = N • The unit is the amount of net force required to accelerate a mass of 1 kilogram at a rate of 1 meter per second squared.

  10. The First and Second Law • Now, if we look back at the first law, we see that the first law is just a special case of the second law when ΣF is zero. ΣF = m*a (2nd law) 0 = m*a m is always bigger than 0 so a = 0 when ΣF= 0 (1st Law)

  11. The Third Law “Lex III: Actionicontrariamsemper et æqualemessereactionem: sivecorporumduorumactiones in se mutuosemperesseæquales et in partescontrariasdirigi.” • It states that whenever a body exerts a force on a second body, the second body exerts an oppositely directed force of equal magnitude on the first body. • Simply “Equal and opposite”

  12. Example of the Third Law • When one runs into someone who weighs just as much, both will bounce off to opposite direction but the same distance. •  However, if one runs into someone who weighs much more, the one will bounce off further (F=ma) in one direction than the heavier one who will bounce off less far (F=ma) to the other direction.

  13. Conclusion • The Newton’s three law of motion is one of the most important and interesting topics in Physics. • The laws might be simple and seem like common senses per se. • However, the connections they have with the real world make it much more valuable and essential. • The laws explain the scientific view of the world: how things move, where things move to, and how far things move.

  14. Conclusion (Cont.) • I look at my desk and see everything is at rest and now, I know it is because there is no net external force such as me pushing them or wind blowing onto them--Newton’s first law of motion. • Now, I push a ball. It moves and stops. It would move forever in the same direction at a constant speed if there was no other force such as friction---Newton’s second law. • I am currently sitting on a chair. I would be falling down to the center of the Earth if the chair and the ground were pushing me back up---Newton’s third law.

  15. As I now notice, Newton’s law of motion is everywhere.

  16. Citation • http://csep10.phys.utk.edu/astr161/lect/history/newton3laws.html • http://hyperphysics.phy-astr.gsu.edu/hbase/newt.html • http://www.grc.nasa.gov/WWW/K-12/airplane/newton.html • http://en.wikipedia.org/wiki/Philosophi%C3%A6_Naturalis_Principia_Mathematica

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