expansion volume

7/23/2019 expansion volume

1/11

Thermal ExpansionThermal Expansion


2/11

Hole SizeHole Size

A rectangular sheet of metal has a circular hole. WhatA rectangular sheet of metal has a circular hole. What

happens to the size of the hole when the metal ishappens to the size of the hole when the metal is

heated?heated?

A) It gets larger.A) It gets larger.

B) It gets smaller.B) It gets smaller.

C) It stays the same.C) It stays the same.


3/11

Microscopic SpacingMicroscopic Spacing

Atoms are in constantAtoms are in constant

motion.motion.

Viration increases withViration increases with

temperaturetemperature

!pacing increases with!pacing increases with

temperaturetemperature


4/11

Change in VolumeChange in Volume

"he #olume of matter"he #olume of matter

e$pands when the atomice$pands when the atomic

spacing increases.spacing increases.

Increase temperatureIncrease temperature %%increase #olume.increase #olume.

A #olume increase is theA #olume increase is the

same as a density decrease.same as a density decrease.

TVV =0

T

V

T + T

V + V


5/11

Coefficient of Volume ExpansionCoefficient of Volume Expansion

&or small #olume changes&or small #olume changes

the relationship etweenthe relationship etween

#olume and temperature is#olume and temperature is

linear.linear.

"he coefficient of #olume"he coefficient of #olume

e$pansion ise$pansion is ..

'aterial'aterial CoefficientCoefficient

(uartz(uartz $ * $ *+,+,CC++

-yre$ glass-yre$ glass $ * $ *+,+,CC++

/lass/lass 01 $ *01 $ *+,+,CC++

!teel!teel 23 $ *23 $ *+,+,CC++

AluminumAluminum 13 $ *13 $ *+,+,CC++

'ercury'ercury 4* $ *4* $ *+,+,CC++

WaterWater 0* $ *0* $ *+,+,CC++

/asoline/asoline 3* $ *3* $ *+,+,CC++

5thyl alcohol5thyl alcohol ** $ *** $ *+,+,CC++

AirAir6 atm)6 atm) 27** $ *27** $ *+,+,CC++

TVV =0


6/11

Gas TankGas Tank

A 10 8 steel gas tan9 is openA 10 8 steel gas tan9 is open

and filled to the top withand filled to the top with

gasoline:gasoline: ; 3* $ *; 3* $ *+,+,CC++::

at 4at 4 C. "he car sits in theC. "he car sits in thesun and reaches asun and reaches a

temperature of 20temperature of 20 C.C.

s cool


7/11

Cold WaterCold Water

'ost sustances e$pand'ost sustances e$pand

uniformly with temperature.uniformly with temperature.

Water does not follow theWater does not follow the

pattern.pattern.

Below 7Below 7 C water e$pandsC water e$pands

as it coolsas it cools

Very cold water stays on topVery cold water stays on top

Ice is e#en less denseIce is e#en less dense


8/11

Stretching SolidsStretching Solids

T

L

T + T

L + L

!olids can ha#e dimensions!olids can ha#e dimensions

that are @uite different.that are @uite different.

"he long dimension may"he long dimension may

matter most.matter most.

&ocus on one dimension&ocus on one dimension

ther changes are stillther changes are still

present: less magnitudepresent: less magnitude


9/11

Linear ExpansionLinear Expansion

"he change in #olume"he change in #olume

applies to the threeapplies to the three

dimensions.dimensions.

If the change is e@ual in allIf the change is e@ual in all

directionsdirections is split in thirds.is split in thirds.

"he coefficient of linear"he coefficient of linear

e$pansion in solids 6e$pansion in solids 6) is) is

usually one third ofusually one third of ..

WHLHWLWLHV

WHLV

++

=

000000

0000

)3

(

)3

(

)3

(

000

000

000

WTHL

WHTL

WHLTV

+

+

3/

0

=

= LTL


10/11

Seasonal ChangesSeasonal Changes

"he steel ed of a"he steel ed of a

suspension ridge is 0** msuspension ridge is 0** m

long at 0*long at 0* C.C.

If the temperature goes fromIf the temperature goes from

+2*+2* C to 7*C to 7* C: whatC: what

contraction and e$pansion iscontraction and e$pansion is

possile?possile?

se linear e$pansion.se linear e$pansion.

!ol#e for!ol#e for LL;; LL**T.T.

&irst in winter:&irst in winter:

660 $ *0 $ *+,+,CC+)+))60** m)6+3*)60** m)6+3* C)C)

LL;; +*.0 m+*.0 m

"hen in summer:"hen in summer:

660 $ *0 $ *+,+,CC+)+))60** m)60*)60** m)60* C)C)

LL

;; *.*74 m*.*74 m


11/11

Thermal StressThermal Stress

A change in length isA change in length is

associated with a stress.associated with a stress.

"emperature change causes"emperature change causes

a change in length.a change in length.

If the stress is due toIf the stress is due to

temperature: it>s a thermaltemperature: it>s a thermal

stress.stress.

next

0L

LY

A

F =

0LTL =

TY

L

YLT

A

F=

=

0

0
http://p210_12c.ppt/http://p210_12c.ppt/

expansion volume

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