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Introduction to Physics


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Introduction to Physics

  1. 1. Introduction to Physics Unit 1 Class 1 E. Alexander Burt Potomac School
  2. 2. What is Physics? <ul><li>Start with the root of the word: Physics – physical – think bodies. </li><ul><li>Not human bodies! Bodies in the old sense of the word – think objects.
  3. 3. Objects of all sizes – from subatomic particles all the way up to galactic superclusters! </li></ul><li>So physics is the science of the nature and interaction of objects. </li><ul><li>What are the objects like?
  4. 4. What happens when multiple objects “interact” </li><ul><li>Could be collisions
  5. 5. Could be other forces. </li></ul></ul></ul>
  6. 6. An analogy to sports <ul><li>Suppose you're watching a sport that you have never seen before: </li><ul><li>The book uses a baseball analogy
  7. 7. My own experience is Lacrosse </li></ul><li>As you watch, some things are “legal moves” and some are not. </li><ul><li>So you develop a “theory” about what's a legal move.
  8. 8. And you confirm or change your theory by watching more moves. </li></ul></ul>
  9. 9. So... <ul><li>The job of physics is to figure out the rules to an unknown game called “nature” </li><ul><li>We have a pretty good set of rules so far, thanks to about 2000 years worth of work. (Most of that work is in the last 400 years.) </li><ul><li>For example, we can predict the next solar eclipse. See </li></ul><li>But our rules do not cover all situations. There are areas where physics does not have the answers! </li><ul><li>For example, we still do not understand how gravity actually works! </li></ul></ul></ul>
  10. 10. Branches of Physics <ul><li>Motion and Forces – known by their Greek names “Kinematics and Dynamics”
  11. 11. Electricity and Magnetism
  12. 12. Light and Optics
  13. 13. Heat and Thermodynamics
  14. 14. “Modern Physics” (meaning, roughly, since 1900) </li><ul><li>Relativity
  15. 15. Quantum Mechanics </li></ul></ul>
  16. 16. Mathematics Spoken Here <ul><li>Love it or hate it, the language of physics is math. </li><ul><li>The “rules of the game” we were talking about earlier are expressed most concisely in mathematical form.
  17. 17. These rules take the form of equations, and the equations can be used to predict future events. </li></ul><li>That's really important, so I'm going to repeat it: The “laws of physics” are mathematical expressions which can be used to make predictions. </li></ul>
  18. 18. The Basic Vocabulary: Units <ul><li>Math is all about measured quantities
  19. 19. Quantities of what? </li><ul><li>A gallon of gasoline is different than a pound of hamburger, and they're both different than 45 minutes of physics class </li></ul><li>Fundamental units: (The big three. There are others) </li><ul><li>Length
  20. 20. Mass
  21. 21. Time </li></ul></ul>
  22. 22. Le Systeme Internationale (vive la France!) <ul><li>Meters – supposedly 1/10,000,000 the distance from the north pole to the equator... NOT!
  23. 23. Kilograms – supposedly the mass of one cubic decimeter of water
  24. 24. Seconds – the usual. Decimal time never really did catch on.
  25. 25. Prefixes – to make the basic stuff bigger or smaller. See p. 7 in the text. </li></ul>