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General Physics A PHY 2048C

General Physics A PHY 2048C. Prof. Harrison Prosper Prof. Sharon Hagopian Prof. Yuko Hori Prof. Takemichi Okui. Welcome to PHY 2048C!. Lectures Learn and discuss principles Tutorials Reviews and problem solving Labs Learn basic experimental techniques. Welcome to PHY 2048C!.

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General Physics A PHY 2048C

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  1. General Physics APHY 2048C Prof. Harrison Prosper Prof. Sharon Hagopian Prof. Yuko Hori Prof. Takemichi Okui

  2. Welcome to PHY 2048C! • Lectures • Learn and discuss principles • Tutorials • Reviews and problem solving • Labs • Learn basic experimental techniques

  3. Welcome to PHY 2048C! Textbook Essential University Physics, Volume 1 Richard Wolfson Pearson Addison Wesley with MasteringPhysics http://www.masteringphysics.com

  4. Welcome to PHY 2048C! Personal Response System You may use your PRS “clicker” to answer questions in class if you wish to earn extra credit.

  5. Welcome to PHY 2048C! Grades • Mini-Exams 20% • Mid-Term Exam 20% 65% • Final Exam 25% • Labs 15% • Homework 20%

  6. What is Physics? The study of • Matter • Energy • Time • Space

  7. Humanity’s Greatest Discovery The Universe is understandable Why? Because the Universe works according to definite rules… …that seem always to be the same.

  8. Humanity’s Greatest Discovery Example: A well-known rule If you travel between two points separated by a distance D at constant speed V, you will cover the distance in time T = D / V

  9. Humanity’s Greatest Discovery Example: We know enough about the rules that govern the behavior of the Sun to predict, with very high confidence, that the Sun can shine for another 5 billion years.

  10. Chapter 1: Doing Physics

  11. IDEA Physics is simple at the level of principle, but challenging at the level of application. Alas, there is no easy path to success.However, having a strategy can be useful: Interpret Develop Evaluate Assess

  12. Units

  13. Units Système International Units • Length meter (m) • Time second (s) • Mass kilogram (kg)

  14. Units Système International Units • Electric current ampere (A) • Temperature kelvin (K) • Amount of substance mole (mol) • Luminosity candela (cd)

  15. Units Units are important! http://www.cnn.com/TECH/space/9909/30/mars.metric.02 A $125-million mistake

  16. Operational Definitions • Defined by procedures that can be replicated in any suitably equipped laboratory. • The second and the meter are defined operationally. • But the kilogram, as yet, is not.

  17. Operational Definitions United States Time Standard NIST-F1: Accurate to 1 second in 80 million years Wikimedia Commons

  18. Operational Definitions Definition of the second (1967) The duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.

  19. Operational Definitions Definition of the meter (1983) The meter is the distance traveled by light in vacuum during a time interval of 1/299,792,458 of a second. The speed of light is now defined to be exactly299,792,458 meters per second.

  20. Definition of Kilogram International Prototype Kilogram • Kept at the International Bureau of Weights and Measures at Sèvres, France. • Made of a platinum-iridium alloy.

  21. Working with Numbers

  22. Working with Numbers A Couple of Large Numbers • The radius of the observable universe is about 100,000,000,000,000,000,000,000,000 m • The US federal budget is about $ 3,000,000,000,000

  23. Working with Numbers A Small Number • The top quark lasts for about 1/1,000,000,000,000,000,000,000,000 s

  24. Working with Numbers Scientific Notation • 1 x 1026 m radius of universe • $3 x 1012US federal budget • 1 x 10-24 s top quark lifetime

  25. Powers of 10 10-9 nano (n) 10-6 micro (μ) 10-3 milli (m) 103 kilo (k) 106 mega (M) 109 giga (G)

  26. Accuracy & Significant Figures • Every measurement has a degree of uncertainty. • Therefore, it makes sense to round off numbers in some reasonable way.

  27. Accuracy & Significant Figures Example: • A square table has a measured area of 3.5 m2. • The square root of this number is 1.870828693 m. But, it would be absurd to give this as the length of each side of the table. Why?

  28. Estimation

  29. Estimation 1. What’s the total force of air on your body? 2. How high would a stack of 3 trillion 1-dollar bills be? 3. How many drops of rain fall on Tallahassee during a 1-hour tropical storm?

  30. Estimation 4. How much solar energy is intercepted by the Earth per second? Data: The Earth’s radius is about 6.4 x 106 m The Sun is on average 150 million km away from the Earth. The energy output of the Sun is about 4 x 1026 joules / second

  31. Estimation 5. In 2005, the energy used per second in the United States was about 3.3 terrajoules / second. Suppose we covered part of Arizona with solar cells, each with an efficiency of 15%, what fraction of the area of the state would be needed to match this consumption rate? Area of Arizona: 295,254 km2

  32. Summary • The Universe is governed by rules. • Physics is the study of these rules and their consequences. • Units are important. • Operational definitions are useful way to standardize units. • Every measurement is uncertain.

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