Announcements 9/13/10 5 students still haven’t registered their clickers. Be sure to register them via the course website. a. Check your scores via the course website! – Make sure you have scores listed under the “Clicker Quizzes” category. Mathematica T-shirt today in honor of the first Mathematica problem due tonight. Mathematica is available in N212, N337, and possibly other computer labs. a. To get into those two rooms, you need the combination from dept secretary Diann. b. To use the computers in those rooms, you need a departmental computer account (form on dept website, under “computer support”). I will hold my office hours in N337 today, and will go over the “Basic commands of Mathematica” handout from course website. Hopefully several computers will be available. TA’s office hours still in underground lab.
Announcements 9/13/10 5 students still haven’t registered their clickers. Be sure to register them via the course website. a. a.Check your scores via the.
Dec 21, 2015
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Announcements 9/13/10 5 students still haven’t registered their clickers. Be sure to
register them via the course website.a. Check your scores via the course website!
– Make sure you have scores listed under the “Clicker Quizzes” category.
Mathematica T-shirt today in honor of the first Mathematica problem due tonight. Mathematica is available in N212, N337, and possibly other computer labs.
a. To get into those two rooms, you need the combination from dept secretary Diann.
b. To use the computers in those rooms, you need a departmental computer account (form on dept website, under “computer support”).
I will hold my office hours in N337 today, and will go over the “Basic commands of Mathematica” handout from course website. Hopefully several computers will be available.
TA’s office hours still in underground lab.
Quick Writing
In light of what we discussed last lecture, how would you describe temperature on the microscopic level?
Height Histogram (made up data): Total students = 49 Round heights to closest
integer, plot histogram What is the combined area
of all bars? If I pick a student at random,
what are chances he/she will be 68 inches tall?
What is the area of the bar at 68 inches divided by the total area?
How many students will be exactly 68.000000 inches tall?
If I pick a student at random, what are chances he/she will be 61.5-64.5 inches tall?
What is average height of all students? (At least, how would you figure that out?)
“Normalized” Histogram: Total students = 49 Y-axis now divided by
total # of students. What is combined area of
all bars? If I pick a student at
random, what are chances he/she will be 61.5-64.5 inches tall? (At least, how would you figure that out?)
How many students have heights between 61.5 and 64.5 inches?
What is average height of all students?
Probability Distribution Function
Imagine total # =10 billion. Tiny “bins”. Connect peaks of curve with line… becomes a function
What is combined area of all bars? If I pick a person at random, what are chances he/she
will be 63.6-67.2 inches tall? How many people have heights between 63.6 and 67.2
inches? What is average height of all people? (If a non-
symmetric curve, this is not just the peak of the curve.)
Velocity Distribution: “Maxwell-Boltzmann”
How many molecules with speeds between 200 and 300 m/s?
What is “vmost probable”? What is “vaverage”? What is “vrms”? How many molecules
are at exactly the “most probable” velocity?
2122( ) Bmv k Tf v v e
with some constantsout in front tonormalize itWhere does this eqn come from? Wait a few weeks.
Calvin and Hobbes, Bill Watterson
Calvin and Hobbes, Bill Watterson
Calvin and Hobbes, Bill Watterson
Calvin and Hobbes, Bill Watterson
An ideal gas has a mixture of heavy and light monatomic molecules at the same temperature. Which molecules will have the most kinetic energy (on average)?
a. heavyb. lightc. same
Thought question
Heat = not a fluid!
Sir Benjamin Thompson, Count Rumford, 1753-1814
a. Boiling water with a cannon
Image credit: Wikipedia
James Joule, 1818-1889
Image credit: Wikipedia
Demo/Video
Demo: Boiling water with a vacuum
Video: Boiling water in a paper cup
Reading Quiz What name do we give to the heat
capacity per unit mass? a. entropy b. internal energyc. mass-pacityd. normalized heat capacitye. specific heat
Specific Heat
Q=mcT
Thought Question If you add 500 J of
heat to a mass of water, and 500 J of heat to the same mass of copper, which one increases the most in temperature?
a. Waterb. Copperc. Same
Reading Quiz
Thermal energy that is used to melt or freeze something is called:
a. latent heatb. mass heatc. melty-freezy heatd. molar heate. specific heat
Phase Changes
T
Heat energy added (Q)
100o C Water boils
0o C Ice melts
Ice warming
Ice melting
Water warming
Water boiling
Steam warming
Latent Heats
Thought Question If you want to melt a cube of ice
that’s initially at -40 C, which part takes the most energy?
a. Raising the temperature b. Converting from solid to liquid
phasec. Same
Calorimetry
Worked problem (class designed):____ grams of hot iron at _____ C is added to ____ g of water at _____ C in a styrofoam insulated container. What is the final temperature of the mixture? (Neglect the container.)
ciron = 448 J/kgC cwater = 4186 J/kgC Lwater-steam = 2.26 106 J/kg
Related Documents
