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Please sit together in pairs: Michael A. and Lisa Barney and Joseph B. Thomas and Hao-Chien

Arielle and Rebecca Mikhail and Katherine Yujia and Yiran Valerie and Joseph Seb. Kevin and Quanbiao Allison and Charles Matt M. and Lu Morgan and Ashkan Laura and Naichen Lauren and Dale Michael O. and Disha Hannah and Efrain James and Da Nicholas and Heran Ben and Joseph Ser.

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Please sit together in pairs: Michael A. and Lisa Barney and Joseph B. Thomas and Hao-Chien

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  1. Arielle and Rebecca • Mikhail and Katherine • Yujia and Yiran • Valerie and Joseph Seb. • Kevin and Quanbiao • Allison and Charles • Matt M. and Lu • Morgan and Ashkan • Laura and Naichen • Lauren and Dale • Michael O. and Disha • Hannah and Efrain • James and Da • Nicholas and Heran • Ben and Joseph Ser. • Please sit together in pairs: • Michael A. and Lisa • Barney and Joseph B. • Thomas and Hao-Chien • Glenn and Stephen • Ann and Qihan • John and Tyson • Meaghan and Nicole • Korey and Edward • William and Zhenmin • Michael W. and Taehoon • Zach and Shenheng • Casey and Matt R. • Audrey and Shiyue • Lisette and Evan Phys 150 Lecture 2

  2. Announcements • Chapters 1 and 2 are available online (see the 150 web page). • There will be a Quiz on Chapter 2 on Tuesday at the beginning of class. • Homework 1 is due on Monday at midnight. Please go to the 150 web page. • i>clickers are required starting Tuesday. Please register via the 150 web page. Phys 150 Lecture 2

  3. Explosions Cannon • Rapidly expanding hot gas Phys 150 Lecture 2

  4. Explosions Cannon • Rapidly expanding hot gas Comet Shoemaker-Levy 9 1994 Phys 150 Lecture 2

  5. Explosions • Kinetic energy = energy of motion = ½ mv2 Extinction of dinosaurs 65 million years ago Phys 150 Lecture 2

  6. Power Bulbs • 100 Watt incandescent light bulb • Most of the power is producing heat, not light • 26 Watt Compact Fluorescent Light (CFL) • Same light output with ¼ the energy use! • Light Emitting Diode (LED) • About same energy efficiency as CFL Phys 150 Lecture 2

  7. Power Bulbs • 100 Watt incandescent light bulb • Most of the power is producing heat, not light • 26 Watt Compact Fluorescent Light (CFL) • Same light output with ¼ the energy use! • Light Emitting Diode (LED) • About same energy efficiency as CFL Phys 150 Lecture 2

  8. Human energy consumption 100 Watts needed to fuel your bodily functions • Eventually given off as heat • The amount of energy you burn per day is thus about • 100 Watts x 20 hours ≈ 2000 Watt-hours = 2 kWh • kilowatt-hour (kWh) is a commonly used unit of energy (kilowatt = 1000 Watts) Phys 150 Lecture 2

  9. i>clicker question A typical adult needs to consume about 2000 Calories/day. Find the relationship between Calories and kWh. • Cal ≈ kWh • 10 Cal ≈ kWh • 100 Cal ≈ kWh • 1000 Cal ≈ kWh Phys 150 Lecture 2

  10. i>clicker question A typical adult needs to consume about 2000 Calories/day. Find the relationship between Calories and kWh. • Cal ≈ kWh • 10 Cal ≈ kWh • 100 Cal ≈ kWh • 1000 Cal ≈ kWh Consume per day = Burn per day • 2000 Cal/day ≈ 2 kWh • 1000 Cal ≈ kWh Phys 150 Lecture 2

  11. Energy units • Calorie (Cal) • kilowatt-hour (kWh) • British Thermal Unit (BTU) • Joules (J) – BTU ≈ 1000 J 1000 Cal ≈ 1 kWh ≈ 4000 BTU Phys 150 Lecture 2

  12. Energy units • Calorie (Cal) • kilowatt-hour (kWh) • British Thermal Unit (BTU) • Joules (J) – Watt = J/s 1000 Cal ≈ 1 kWh ≈ 4000 BTU Phys 150 Lecture 2

  13. i>clicker question A typical home in the US requires about a kW of electric power (without AC). How much electric power do you need to power a million homes? • kilowatt • Megawatt • Gigawatt • Terawatt Phys 150 Lecture 2

  14. i>clicker question A typical home in the US requires about a kW of electric power (without AC). How much electric power do you need to power a million homes? • kilowatt (kW) = 1000 W = 103 W • Megawatt (MW) = 1,000,000 W = 106 W (million) • Gigawatt (GW) = 1,000,000,000 W = 109 W (billion) • Terawatt (TW) = 1,000,000,000,000 W = 1012 W (trillion) A large electric power plant generates about a Gigawatt of electric power Phys 150 Lecture 2

  15. i>clicker question A typical home in the US requires about a kW of electric power (without AC). How much electric power do you need to power a million homes? kW x 1,000,000 = 1000 W x 1,000,000 = 1,000,000,000 W = Gigawatt kW x 106 = 103 W x 106 = 109 W = Gigawatt Calculator: 1 EE 3 x 1 EE 6 = 1 09 Phys 150 Lecture 2

  16. Types of Energy • Chemical energy • Chemical energy • Heat energy = Thermal energy • Kinetic energy = energy of motion = ½ mv2 • Electric energy • Light energy • Nuclear energy ≈ 106 x chemical energy Phys 150 Lecture 2

  17. Light energy • Light energy (solar energy) Solar motor Phys 150 Lecture 2

  18. i>clicker question The amount of power in one square meter of sunlight (with the sun directly overhead) is about • 1000 BTU • 1000 Calories • 1 kWh • 1 kW Phys 150 Lecture 2

  19. i>clicker question The amount of power in one square meter of sunlight (with the sun directly overhead) is about • 1000 BTU • 1000 Calories • 1 kWh • 1 kW meter2 of sunlight ≈ 1 kW Phys 150 Lecture 2

  20. Solar automobiles • Typical automobile uses 50 – 400 hp meter2 of sunlight ≈ 1 hp Solar car Phys 150 Lecture 2

  21. Solar airplanes Zephyr – flew for 2 weeks meter2 of sunlight ≈ 1 hp Zephyr Phys 150 Lecture 2

  22. 1 kW ≈ 1 hp ≈ meter2 of sunlight Phys 150 Lecture 2

  23. i>clicker question The amount of power in one square kilometer of sunlight (with the sun directly overhead) is about • 1 kW • 1 MW • 1 GW • 1 TW Phys 150 Lecture 2

  24. i>clicker question The amount of power in one square kilometer of sunlight (with the sun directly overhead) is about • 1 kW • 1 MW • 1 GW • 1 TW • km2 = 103 m x 103 m = 106 m2, so • km2 sunlight = 106 x kW = 106 x 103 W = GW • Same as a large power plant Phys 150 Lecture 2

  25. Solar Photovoltaic (PV) cells • Inexpensive ones are 10% efficient • Expensive ones are 40% efficient Phys 150 Lecture 2

  26. Hydrogen Fuel Cell • 2 H2 + O2 = 2 H2O + energy Phys 150 Lecture 2

  27. i>clicker question Most of the Hydrogen we use for power comes from • Pockets of Hydrogen gas found underground • Hydrogen gas extracted from the atmosphere • Hydrogen produced in nuclear reactors • Hydrogen manufactured from fossil fuels and/or water Phys 150 Lecture 2

  28. i>clicker question Most of the Hydrogen we use for power comes from • Pockets of Hydrogen gas found underground • Hydrogen gas extracted from the atmosphere • Hydrogen produced in nuclear reactors • Hydrogen manufactured from fossil fuels and/or water Phys 150 Lecture 2

  29. Hydrogen Fuel Cell • 2 H2 + O2 = 2 H2O + energy • Energy + 2 H2O = 2 H2 + O2 Electrolysis Phys 150 Lecture 2

  30. Hydrogen CH4 = methane Fuel Cell • 2 H2 + O2 = 2 H2O + energy • Energy + 2 H2O = 2 H2 + O2 • Energy + 2 H2O + CH4 = 4 H2 + CO2 Electrolysis Phys 150 Lecture 2

  31. Hydrogen CH4 = methane Fuel Cell • 2 H2 + O2 = 2 H2O + energy • Energy + 2 H2O = 2 H2 + O2 • Energy + 2 H2O + CH4 = 4 H2 + CO2 • Hydrogen is not a source of energy. It is only a means of transporting energy. • but Electrolysis H2 has 3x more energy per gram than gasoline H2 (compressed gas) has 6x less energy per gallon than gasoline Phys 150 Lecture 2

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