1. Announcements 9/7/11 Prayer Small change to HW policy – see email Class directory New student who talked to me yesterday: please see me (I’ve forgotten your name, my apologies) (1+x) n ≈ 1 + nx Frank & Ernest

2. Reading quiz (graded): Which two temperature scales have the same sized intervals, varying only in their choice of the zero point? a. a.Fahrenheit and Celsius b. b.Fahrenheit and Kelvin c. c.Fahrenheit and Pentatonic d. d.Kelvin and Celsius e. e.Kelvin and BTU

3. Temperature Temperature scales What’s a thermometer?

4. Demos: Liquid bulb thermometer Constant volume thermometer

5. Thermal contact Two objects in “thermal contact” will come to “thermal equilibrium”, and then have the same “temperature”. What is thermal contact? What is thermal equilibrium? What is temperature? a. a.Is there a maximum temperature? b. b.Is there a minimum temperature?

6. Thermal expansion What went wrong here?

7. Thermal Expansion The equation:  = “________________” For reference:  steel = 11  10 -6 /  C

8. Thought question (ungraded) You heat a disc with a hole in it. Will the radius of the hole get larger, smaller, or stay the same? a. a.Larger b. b.Smaller c. c.Stay the same

9. Videos/Demo: Demo: Ring & Ball Demo: Bimetallic strip Video: Bimetallic strip

10. Thought question (ungraded): If the expansion of all of the linear dimensions of an object is by a factor of 10 -5 per degree, what should be the expansion factor of the surface area of the object? a. a.10 -5 per degree b. b.2  10 -5 per degree c. c.10 -10 per degree

11. Area & Volume Expansion (of solids) The equations:  = …

12. Thought question (ungraded): Two jars of gas: helium and neon. Both have the same volume, same pressure, same temperature. Which jar contains the greatest number of gas molecules? (The mass of a neon molecule is greater than the mass of a helium molecule.) a. a.jar of helium b. b.jar of neon c. c.same number

13. Ideal Gas Law Hold T constant, then as P increases V will decrease Hold P constant, then as T increases V will increase Hold P, T, constant, then as #molecules increases V will increase Summary:

14. Ralph is confused…the book calls two different equations “the ideal gas law”: “PV = nRT”, and “PV = Nk B T”. Why are they both called the ideal gas law, when only the first equation looks like what he learned in chemistry? Quick Writing Important stuff: P must be in _______ V must be in _______ T must be in _______ n = ________ R = ________ N = ________ k B = ________ What’s a mole? How are R and k B related? Units of P  V?

15. Molecules collide like superballs (elastic) due to repulsive forces No attractive forces Never condense into liquids or solids Are like “frictionless surfaces”, “massless pulleys”, fluids without viscosity, projectiles without air resistance, etc.  That is, they don’t really exist, but are useful constructs Ideal Gases:

16. Video: “Barrel crush” Image from Wikipedia: http://en.wikipedia.org/wiki/Atmospheric_pressure http://en.wikipedia.org/wiki/Atmospheric_pressure Bottle sealed at 14,000 feet Picture at 9,000 feet Picture at 1,000 feet

17. Demos/Videos: Demos: Liquid nitrogen! a. a.Two balloons b. b.Rubber nail c. c.“Balloon pop” d. d.“Nitrogen Tower” Calculation (if time): How much volume will 1 liter of liquid nitrogen fill when it becomes gas?  Density of LN = 0.807 g/cm 3  Molar mass of N 2 = 28 g/mol  Temperature in this room = 70  F  Atmospheric pressure in Provo today? 0.85 atm Answer: 821 L