1 Temperature Thermal Expansion

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THERMODYNAMICS

Lyza Marie G. Luchico


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LETS COMPUTE

Imagine Juan dela Cruz will spendPhP 60,000 for tuition fees for 4years (2 semesters per year) and hasan allowance of PhP 200 (Assuming20 days in a month for 10 months).He is also spending at least PhP 500

per project each semester and has acontingency of PhP 200 persemester. What is the least amount

of money Juans parents will spend


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EDUCATION

EXPENSESPhP 525,600*

*Assuming no tuition feeincrease and other expenses


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PART 2: ORIENTATION

0 Orientation Phys 104.pptx
http://localhost/var/www/apps/conversion/tmp/scratch_9/0%20Orientation%20Phys%20104.pptxhttp://localhost/var/www/apps/conversion/tmp/scratch_9/0%20Orientation%20Phys%20104.pptx


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Thermodynamics

study of energy transformations

HeatMechanical work

Other aspects of energy

Study of the relationship ofenergy transformationsto the

properties of matter.


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Temperature and Heat

Measure of

hotnessand

coldnessof an

object

Amount of energy

that transfers from

a body of highertemperatureto

another body of

lower temperatureLength of an objectSteam Pressure

ability to conduct

electricity

color

Heat Flow:

Tto T


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Thermometer

It is a thermal sensorthat

measures temperature.

It is any material that has a

thermometric property.

Property of an object which

changeswith temperature


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Thermocouple


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Thermal Contact

Energy exchange between two objects

due to temperature difference

Thermal Equilibrium

A situation in which two objects wouldnot exchange energy by heat transfer ifthey were placed in thermal contact.


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Temperature Scales

1] Celsius (oC)Anders Celsius

2] Fahrenheit (oF)Daniel Fahrenheit

3] Kelvin (K)Lord Kelvin

4] Rankine (oR)William Rankine


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Temperature Scales

o


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Temperature Scales

Temperature

Scales

Celsius

o

C)

Kelvin

K)

Fahrenheit

o

F)

Rankine

o

R)

Freezing

Point of H20

0 273.15 32 491.67

BoilingPoint of H20

100 373.15 212 671.67

100 Co 100 K 180 Fo 180 Ro

100 Co = 100 K

Co = K

180 Fo = 180 Ro

Fo = Ro


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Absolute Temperature Scale


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Temperature ScalesTemperature Scale Absolute Zero Triple Point of H

2

0

Celsius (oC) -273.15 0.01

Fahrenheit (oF) -459.67 32.018

Kelvin (K) 0 273.16

Rankine (oR) 0 491.688

Triple Point of Wateris when liquid

water, gaseous water and solid

water co-existin equilibrium.

At absolute zero, a system of

molecules has its minimumpossible

total energy.


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TEMPERATURE SCALES

COMPUTATION

3. A bottle of soft drink is placed in a

refrigerator and left there until its

temperature drops by 15 K fromits original value. What is the

corresponding change in

temperature on the Fahrenheitscale?


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PAIR SHARE

If I will measure my

temperature in terms of my

understanding of the

lesson, what would it be?

What heat will I include toincrease the temperature?


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PAIR SHARE

Materials expand when

heated, does thismean mass is added

to the material?Explain


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Thermal Expansion

It is a phenomenon that as the

temperatureof solids and liquids

increases, length and volume

increases.

It is the consequence of the change

in the average separationbetween atoms in an object.


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Linear Expansion

L is directly proportional to T

L is directly proportional to Lo


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Linear Expansion

where:

L is the change in lengthLois the initial length

T is the change in temperature, Coor K

is the coefficient of linear expansion,

1/Co

or 1/K


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Volume Expansion

V is directly proportional to T

V is directly proportional to Vo

where:

V is the change in volumeVois the initial volume

T is the change in temperature, Coor K

is the coefficient of volume expansion,

1/Coor 1/K


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Thermal Expansion

1] Linear Expansion:

2] Volume Expansion:


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Example No. 1

A surveyor uses a steel measuring tape

that is exactly 50.000 m long at a

temperature of 20oC. What is its length

on a hot summer day when thetemperature is 35oC where the

coefficient of linear expansion, , of

steel is 1.2 x 10-5/Co.


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Example No. 2

The average coefficient of volume

expansion for carbon tetrachloride is

5.81 x 10-4(Co)-1. If a 50.0-gal steel

container (1gal = .003785 m3) is filledcompletely with carbon tetrachloride

when the temperature is 10oC, how much

will spill over in cm3when the

temperature rises to 30oC?


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Thermal Expansion

1] Linear Expansion:

2] Volume Expansion:


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Check your understanding

A bimetallic metal strip is made

of brass [ = 19 x 10-6(Co)-1] and

steel [ = 12 x 10-6(Co)-1]. If the

strip is cooled, in whichdirection will it bend?

A B


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A bimetallic metal strip is made

of brass [ = 19 x 10-6(Co)-1] and

steel [ = 12 x 10-6(Co)-1]. If the

strip is cooled, in whichdirection will it bend?

A B


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Does holes expand or contract when the

temperature increases?

A hole in a piece of solid material expands

when heated just as if it were filled with

the material that surrounds it.


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Problem No. 3

A gold engagement ring has an inner

diameter of 1.5 x 10-2m at a temperature

of 27oC. The ring falls into a container of

hot water whose temperature is 49oC.What is the change in the diameter of

the hole in the ring?

(Au

= 14 x 10-6Co-1

)


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SEATWORK 1

A circular copper ring at 20 degree

Celsius has a hole with an area of

9.980 cm

2

. what minimumtemperature must it have so that it

can slipped onto a steel having a

cross sectional area of 10.000 cm2

?CHALLENGE: Suppose they are

heated simultaneously?


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The figure shows the cross-

sectional view of three cylinders

A, B, and C. One is made from

lead, one from brass and one fromsteel. All three have the same

temperature and the they barely

fit inside each other. As the

cylinders are heated to the same

high temperature, C falls off while

A becomes tightly wedge against

B. Which cylinder is made from

which material?


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Substanc

e

C

o

)

-1

Brass 19 x 10-6

Lead 29 x 10-6

Steel 12 x 10-6

A B C

1. Brass Lead Steel

2. Lead Steel Brass

3. Steel Brass Lead4. Brass Steel Lead

5. Lead Brass Steel

6. Steel Lead Brass

C falls off while A

becomes tightly wedge

against B


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Example No. 4

A brass ring of diameter 10.00 cm at 20oC

is heated and slipped over an aluminum

rod of diameter 10.01 cm at 20oC. To

what temperature must this combinationbe cooled to separate them? Is this

attainable? (Brass= 19 x 10-6C-1;

Al= 24 x 10-6C-1)

What if the aluminum rod were 10.02 cm in

diameter? Is it attainable?


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Seat Work

At 20oC, an aluminum ring has an innerdiameter of 5-cm and a brass rod has adiameter of 5.05-cm. (a) If only the ring

is heated, what temperature must itreach so that it will just slip over therod? (b) If both are heated together,what temperature must they bothreach so that the ring just slips overthe rod? If melting point of aluminumis 660oC, will it work?

(Brass= 19 x 10-6Co -1; Al= 24 x 10

-6Co -1)


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Home Work

An aluminum can is filled to the brim

with a liquid. The can and the liquid

are heated so their temperatures

change by the same amount. The cansinitial volume at 5oC is 3.5 x 10-4m3.

The coefficient of expansion for

aluminum is 69 x 10-6/Co. When the can

and the liquid are heated to 78oC, 3.6 x10-6m3of liquid spills over. What is the

coefficient of volume expansion of the

liquid?


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Expansion of Water

But on a fine scale, it is not exactly linear.


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Expansion of Water


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Expansion of Water

What if water behaves similarly as that of

other liquids were at freezing point, it hasthe smallest volume?

The contraction of water up to 4oChas an

important consequence in marine life.


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Practice Problem

Suppose that the steel gas tank in a car

is completely filled when the

temperature is 17oC. How many

gallons will spill out of the twenty-gallon tank when the temperature

rises to 35oC?

steel

= 12 x 10

-6

/ C

o

gasoline

= 950 x 10

-6

/C

o

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1 Temperature Thermal Expansion