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Things to Know Physics 102: Principles of Physics Professor Lee Carkner Thing you will need
Giancoli, “Physics”, 6th edition Scientific calculator
Bring both to class Lab manual WebAssign card
Help session: TBA (Hopefully Tues, Thurs evenings)
Lab section If you need to add a lab or change labs, fill
out lab form Labs start this Thursday!
How Does the Class Work?
Read the book material before class Do the WebAssign homework
Before class Download and print out class notes http://helios.augustana.edu/~lc/ph102 Be sure to set as “Pure Black and White”
Come to class Do the PAL exercises Answer the Quizdom questions
Lab once a week Three tests and final
WebAssign Homework will be entered and graded online
At webassign.com Click on student login Username is your first and last name together
(e.g. “johnsmith”) Institution is “augustana” Password is same as last semester
Augustana ID number if new to class After login, click on the current assignment and
complete it WARNING: Can only submit it three times
Homework Homework will generally be from book
Will be posted on webpage if you want to look at them without a computer
WebAssign will randomize numbers Available at noon M,W,F Due at midnight Tue, Thu, Sun
Cannot turn homework in late or make up Can drop lowest three
Each homework worth same amount (100 points) 10% of grade Can drop (or miss) three No make-ups or grade changes
PAL
What is PAL? Physics Active Learning
Each class you will get a PAL worksheet
Also will answer questions with Quizdom remotes
Worth 15% of your grade Need to come to class Can drop (or skip) three PAL’s
Grading on Tests and PALs
1. Written answers must be in complete sentences
2. Numbers must have units3. Answers must reasonable
• If not reasonable, explain why
4. All work must be neat and easily readable
Thermodynamics
What is thermodynamics? Thermo
Dynamics
Thermodynamics is the study of thermal and mechanical energy How do you transform one into the
other?
Where Does Thermodynamics Come
From? Back in the early 1800’s people figured out that you can transform thermal into mechanical energy
A heat engine Problem:
Need to understand what is going on in the engine
Temperature How does temperature manifest itself?
e.g., the height of a column of fluid
We still don’t know what temperature is
Thermal Equilibrium
A thermoscope Now put the thermoscope in a cup of water
They are not transferring heat They are at the same temperature
Two bodies at different temperatures placed together will exchange heat until they are in thermal equilibrium (and thus at the same temperature)
Zeroth Law of Thermodynamics
or if a thermoscope placed near one and
then the other reads the same Zeroth Law of Thermodynamics
If two objects are each in thermal equilibrium with a third object then they are also in thermal equilibrium with each other
Thermometers In order for a thermoscope to be a thermometer it
needs to be calibrated Example: the Celsius scale
Put it in ice and mark the height of the column as 0
Fill in the numbers 1-99 (in even intervals) in between
Only tells you temperature relative to the freezing point of water
Types of Thermometers Glass tube
Physics: Increase of length with increasing temperature
Pros:
Cons: Resistance
Physics: Electrical resistance increases with increasing temperature
Pros:
Cons:
Dial Physics: Increased
bending of bi-metal strip with temperature
Pros: Cons:
Radiation Physics: Change in type
and amount of radiation emitted with temperature
Pros:
Cons:
Temperature Scales Gabriel Daniel Fahrenheit invented the mercury
thermometer in 1714
Anders Celsius introduced his scale is 1742
William Thomson, Lord Kelvin, determined from theory that minus 273.15 degrees Celsius is the coldest it can get
The Kelvin Scale In science we normally use the Kelvin scale
Tells you temperature relative to absolute zero,
the coldest anything can get
No negative numbers
TC = TK -273.15TF = 9/5 TC +32
A temperature change of 5 Celsius degrees is equal to a temperature change of 9 Fahrenheit degrees
Thermal Expansion Heating an object causes it to expand
Why?
The degree of expansion depends on the change in temperature and the coefficient of expansion We can measure temperature and look up
coefficient of expansion
Linear Expansion The degree to which the length of an
object changes is given by:L = L T
Where is the coefficient of linear expansion
This applies to all dimensions of a solid length, width and height
Change in length is proportional to length and temperature change
If the linear dimensions of a solid change then the volume must change:
V = V T Where =3
Thermal Expansion and Thermometers
Consider two strips of metal with different coefficients of linear expansion attached together (bimetal strip)
This principle is used in dial thermometers and thermostats