Announcements 9/8/10 Vote for TA office hour times (see ). For HW problem 4-8, you need the bulk modulus of copper. You should get that from Chapter 12 of your book (if you don’t have that chapter, I believe there are some books chained to tables in the Tutorial Lab). I really disliked the order that the book presented things in Chapters 20-22… so I changed the order! (The benefits of being more-or-less in charge. ) a. a.  For Friday, we’re skipping chapter 20 and parts of chapter 21. On Monday, we’ll come back to Chapter 20, and then a week from Monday we’ll come back to Chapter 21.

2 Astronomy Club Opening Social This Friday 5-7 pm Join the BYU Astronomical Society for our opening social Join the BYU Astronomical Society for our opening social This Friday from 5-7 pm in the Pendulum Court of the ESC This Friday from 5-7 pm in the Pendulum Court of the ESC We will have pizza and plan activities for the upcoming semester We will have pizza and plan activities for the upcoming semester Come have fun and see what the best club on campus has to offer Come have fun and see what the best club on campus has to offer You don’t need to be a major, the club is open to anyone with an interest in Astronomy! You don’t need to be a major, the club is open to anyone with an interest in Astronomy! Join our mailing list – go to Join our mailing list – go to a. astroclub astroclubhttp://lists.physics.byu.edu/mailman/listinfo/ astroclub Questions? Contact Dr. Denise Stephens Questions? Contact Dr. Denise Stephens Benefits of Joining the club: - Monthly public star parties - Fun activities each month - Access to telescopes - Public outreach events - Planetarium shows

Thought questions (review): Water flows from the little pipe into the big pipe. Ignore any friction or height change. The volume flow rate on the right will be ______ on the left a. a.greater than b. b.the same as c. c.less than The speed on the right will be ____ times the speed on the left. a. a.1/9 b. b.1/3 c. c.1 d. d.3 e. e.9

Thought question (review): A ball is thrown toward you, spinning so that (as you look at it) the right side of the ball spins toward you, and the left side away. The ball will a. a.“float” more than a nonspinning ball b. b.“sink” faster than a nonspinning ball c. c.curve to your left d. d.curve to your right

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.Kelvin and Celsius d. d.Kelvin and BTU e. e.Fahrenheit and Diatonic

Demos: Liquid bulb thermometer Constant volume thermometer

Thermal expansion What went wrong here?

Videos/Demo: Video: Thermal expansion of wire Demo: Bimetallic strip Video: Bimetallic strip

Thought question (ungraded): If the expansion of all of the linear dimensions of an object is proportional to ΔT, what should the expansion of the surface area of the object be proportional to? a. a.ΔT b. b.ΔT 2 c. c.ΔT 3 d. d.The surface area won’t change with temperature. e. e.None of the above

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

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

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

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

Demos/Videos: Video: “barrel crush” Demo: Liquid nitrogen balloons

Thought question: If I heat up a balloon from 25  C to 50  C, about how much will its volume change? a. a.By less than 10% b. b.By about 50% c. c.By a factor of 2 d. d.By more than a factor of 2 e. e.I’ve no idea