P103 Temperature, Heat, Expansion

7/29/2019 P103 Temperature, Heat, Expansion

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Temperature, Heat, ExpansioBy: Quantum Yuri B. Lubrica


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TEMPERATURE


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Is temperature

the same as

heat?

Quantum Yuri B. Lubrica 2011


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Temperature

The quantity that indicates how wacold an object is with respect to so

standard (Hewitt)

Celsius (centigrade), Kelvin, FahrenRankine



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Thermometers

http://cutebabygear.net/wp-

content/uploads/2011/07/1310868853-84.jpg

The colored contracts and e

dependingtempe

Thermal Equi



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Mercury Thermometers

http://2.bp.blogspot.com/-

a1EdNIFVYEI/TWU090eyXXI/AAAAAAAAAZ4/NHIeBKBKZ1c/s1600/ThermometerMercu

Its phased out

because of the

danger of

mercurypoisoning.



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Kelvin Scale

Calibrated using gas & JosephGay-Lussacs Law (not freezingand boiling points of water).

0 kelvin (-273.15C) =

absolute zero, substance hasno KE to give up. (oscillations =slowest; NOT zero)

http://upload.wikimedia.org/wikipedia/commons/thumb/a/a0/Lord_Kelvi

/250px-Lord_Kelvin_photograph.jpgQuantum Yuri B. Lubrica 2011


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Kelvin S



Figure courtesy

of University

Physics with

Modern Physics

by Young


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William Thomson, 1st Baron K

Baron Kelvin of Largs

House of Lords (UK Parliament)

River Kelvin close to his

laboratory (Scotland)




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Kinetic energy & Tempe

Atoms and molecules morandomly; they have Kine

Energy

average translational KE directly proportional to

temperature.Quantum Yuri B. Lubrica 2011


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Quick Check-up: True or Fal

Temperature is the measure of thekinetic energy in a substance.

FALSE! 1-L of boiling water vs 2-L. 2-L has twice

total KE but the average KE is the same



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HEAT


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Heat is energy in transit

http://whatisthetrend.net/wp-

content/uploads/2011/05/Miam

http:/

/bestuff.com/images/images_of_stuff/210x6

00/dw

yane-wade-37486.jpg

?1173320112



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What is HEAT?

The ENERGY transferredbetween two objects bec

of the temperature differ

between them. (Hewitt) Always from higher T to lo

(if spontaneous)Quantum Yuri B. Lubrica 2011


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What is the UNIT of h

1 cal = 4.186 J1 kcal = 1000 cal = 1 Cal = 4

1 Btu = 778 ft.lb = 252 cal = 1055 J

Joule is the basic unit of eneall forms, including heat.



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Can an object contain

No. Matter contains inter(thermal) energy.

Grand total of all energies

inside a substance.Energy resulting from hea



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Heat depends on:

Mass (more internal energy)

Temperature difference

Specific Heat Capacity



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Quick Check-up

An iron thumbtack and a big iron bremoved from a hot oven. Both hav

same T. When dropped into identic

containers of water of equal T, whiraises the water temperature more



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Answer:

The big iron bolt will because it hasmass and therefore more molecule

more internal energy to impart to t

water. Same ave. KE, same T, different ma



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Which cools faster? Toasted bread or soup?

Hotdogs or Potatoes?

Wood or Metal?

It also takes less heat to warm

these objects up.Quantum Yuri B. Lubrica 2011


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Specific Heat Capacity

The amount of heat pemass required to raise

temperature by one de

Celsius.

Thermal Inertia



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Some specific heat capacities (ca

http://hyperphysics.phy-astr.gsu.edu/hbase/tables

Gold = 0.0301

Mercury = 0.033

Silver = 0.0558

Copper = 0.0923

Al = 0.215

Ethyl Alcohol = 0.58

Water = 1.00

Ice (-10 C) = 0.49

Granite = 0.19

Glass = 0.20

Wood: 0.4-0.5

Human = 0.84

http://hyperphysics.phy-astr.gsu.edu/hbase/tables/sphtt.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/tables/sphtt.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/tables/sphtt.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/tables/sphtt.html


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Caution: Filling is hot!

http://farm1.static.flickr.com/188/3665380

The crustcools much

faster than

the applefilling.



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Caution:

http://focus.aps.org/files/focus/v22/st5/co

Dont confuse specific

heat with thermalconductivity!

Graphite: c is 1.4x

Diamond: k can beup to 19x



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E

xample



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Example from Young

During a bout with the flu, Romme(80kg) ran a fever of 39.0 C instead

normal body temperature of 37.0 C

much heat is required to raise histemperature by this amount? (expr

your answer in Cal)



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Answer:

Q = mcT = (80kg)(0.84 Cal/kg.K)(2.0K= 134 Cal

If it were not for the bodys temperature

regulating systems, taking in energy inform of food would produce measurab

changes in the body temperature. -Yo



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EXPANSION & CONTRACT

Thermal E pansion


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Thermal Expansion@Higher T,

molecules jigglefaster and move

farther apart.

Linear Expansion:

L = LoT


Figure co

Universit

Modern

Th l E i E


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Thermal Expansion Examp

Telephone wires, loosening

lid, dental filling, reinforcinsteel, thermostats, etc.

*A 50.000m long steel rod o

lengthens by 0.009m whe

is increased from 20C to 3



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Expansion Joints

Courtesy of Young

http://upload.wikimedia.org/wikipedia/commons/t

humb/9/95/Saw_Cut_Control_Joint_in_Concrete.jp

g/220px-Saw_Cut_Control_Joint_in_Concrete.jpg



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What if Thermal Expansion isnt consid

Courtesy of Paul Hewitt

Railroadtracks would

buckle, roads

would crack.

= FAILQuantum Yuri B. Lubrica 2011

REFERENCES


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REFERENCES

Conceptual Physics by Pau

Hewitt

University Physics with Mo

Physics 12 edition by YouPowerpoint template from

Templatewise.com


P103 Temperature, Heat, Expansion

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