system of units & fluids properties

8/10/2019 System of Units & Fluids Properties

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SISTEM UNITSISTEM UNIT

DAN CIRIDAN CIRI--CIRICIRI

BENDALIRBENDALIR


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OBJEKTIFOBJEKTIF

BabBab iniini dirangkadirangka untukuntuk membantumembantu pelajarpelajar

mencapaimencapai perkaraperkara berikutberikut::

-- Mengetahui sistem unit yangyang digunakandigunakan

a ama am me anme an en a ren a r..-- MengenalpastiMengenalpasti ciriciri--ciriciri bendalirbendalir yang asasyang asas

dalamdalam aplikasiaplikasi kejuruteraankejuruteraan..

-- MenyelesaikanMenyelesaikan masalahmasalah asas yangasas yangberkaitanberkaitan dengandengan sistemsistem unitunit dandan

ciriciri--ciriciri bendalirbendalir..


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HASIL PEMBELAJARANHASIL PEMBELAJARAN

Di akhir bab ini, pelajar akan dapat menggunakanDi akhir bab ini, pelajar akan dapat menggunakan

ilmu dan kemahiran yang dipelajari untuk:ilmu dan kemahiran yang dipelajari untuk:-- Mendefinisi dan menyenaraikan sistem unitMendefinisi dan menyenaraikan sistem unit

dan ciridan ciri--ciri bendalir yang asas dalam mekanikciri bendalir yang asas dalam mekanik

bendalir.bendalir.-- Memahami ciriMemahami ciri--ciri bendalir seperti jisim,ciri bendalir seperti jisim,

ketumpatan, ketumpatan bandingan, beratketumpatan, ketumpatan bandingan, berat

tentu, kelikatan dinamik dan kelikatantentu, kelikatan dinamik dan kelikatankinematik,kinematik,

-- Menyelesaikan masalah mudah berkaitanMenyelesaikan masalah mudah berkaitan

sistem unit dan cirisistem unit dan ciri--ciri bendalirciri bendalir


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SUB TOPIKSUB TOPIK

BAB 1

SISTEM UNIT CIRI BENDALIR

en a r

Hukum KelikatanNewtn

Bendalir Newtnian

Ciri Bendalir

s em

!er"e#aan SI & BS

Kuantiti Asas

Kuantiti Ter"itan


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BAHAGIAN IBAHAGIAN I


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SISTEM UNITSISTEM UNIT

Kuantiti boleh diterangkan dalam bermacamKuantiti boleh diterangkan dalam bermacam--macammacam

unit.unit.

Ini boleh menyebabkan kekeliruan terutamanya diIni boleh menyebabkan kekeliruan terutamanya di

a am ang e an en a r.a am ang e an en a r. Sebagai contoh :Sebagai contoh : AmericaAmerica SISI

BritishBritish BSBS

Untuk mengelakkan kekeliruan, unit SI akanUntuk mengelakkan kekeliruan, unit SI akandigunakan di dalam pengajaran ini.digunakan di dalam pengajaran ini.

Walaubagaimanapun, penukaran unit untuk kuantitiWalaubagaimanapun, penukaran unit untuk kuantiti

yang asas perlu juga diketahui.yang asas perlu juga diketahui.


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PERBEZAAN : SI UNIT DAN BSPERBEZAAN : SI UNIT DAN BSUNITUNIT

KuantitiKuantiti SI UnitSI Unit BS UnitBS Unit

PanjangPanjang Meter, mMeter, m Kaki, ftKaki, ft

JisimJisim Kilogram, kgKilogram, kg Pound, lbPound, lb

SuhuSuhu Kelvin, KKelvin, K Fahrenheit, FFahrenheit, F

DayaDaya Newton, NNewton, N Pound Force,Pound Force, lbflbf


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SISTEM SISISTEM SI

SISTEM SI

KUANTITI ASAS KUANTITI TERBITAN


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KUANTITI ASASKUANTITI ASAS

KuantitiKuantiti SI UnitSI Unit DimensiDimensi

PanjangPanjang Meter, mMeter, m LL

JisimJisim Kilogram, kgKilogram, kg MM

MasaMasa Saat sSaat s TT

SuhuSuhu Kelvin, KKelvin, K HH

ArusArus Ampere, AAmpere, A II

Keamatan CahayaKeamatan Cahaya CandelaCandela CdCd

Hanya tiga kuaantiti asas yang diperlukan : panjang, masa dan jisim!,T,M"ATAU panjang, masa dan daya !,T,#"$


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KUANTITI TERBITANKUANTITI TERBITAN

HALA$U%ms1'

!ECUTAN%ms('

TENA)A%k*m(s('

DA+A%k*ms('

ISI!ADU%k*m,'

KUASA%k*m(s,'

TEKANAN%k*m1s('

KUANTITITERBITAN


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FAKTOR PENUKARAN UNIT


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TUGASAN 1TUGASAN 1

RujukRujuk

B. R Munson, D. F Young, T H. Okiishi,

Fundamentals of Fluid Mechanics, John

ey, or .

SKIMA JAWAPAN TUGASAN 1SKIMA JAWAPAN TUGASAN 1


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BAHAGIAN IIBAHAGIAN II

CIRICIRI--CIRI BENDALIRCIRI BENDALIR


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BENDALIRBENDALIR

-A .luid is a su"stan/e w0i/0 de.rms/ntinuusl12 r .lws2 w0en su"3e/ted t

s0earin* .r/es . an1 ma*nitude4


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If a fluid is at rest there are no shearing forcesIf a fluid is at rest there are no shearing forcesacting.acting.

All forces must be perpendicular to the planes whichAll forces must be perpendicular to the planes whichthey are actingthey are acting


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PFOFIL HALAJUPFOFIL HALAJUALIRAN DALAM PAIPALIRAN DALAM PAIP


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HUKUM KELIKATAN NEWTONHUKUM KELIKATAN NEWTON

(Newton's Law of Viscosity)(Newton's Law of Viscosity)

In a solid shear strain,In a solid shear strain, , is constant for a fixed shear, is constant for a fixed shearstress ,stress ,..

In a fluidIn a fluid increases for as long asincreases for as long as is appliedis applied -- thethe

fluid flowsfluid flows


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The deformation which this shear stress causes isThe deformation which this shear stress causes is

measured by the size of themeasured by the size of the angleangle and is knowand is know

s ear s ra ns ear s ra n

Shear strain , = x/y


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Rate of shear strainRate of shear strain == /t/t

== x/ytx/yt== (1/y)(x/t)(1/y)(x/t)

== u/u/

Daripada keputusan ujikaji ;Daripada keputusan ujikaji ;

Shear stress,Shear stress, == constant (u/y)constant (u/y)


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dandan

u/yu/y == kadar perubahan halaju terhadapkadar perubahan halaju terhadapkedudukan ykedudukan y

rate of shear strain =rate of shear strain =du/ddu/d

sertaserta

constantconstant == kelikatan dinamik,kelikatan dinamik,


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== (du/dy)(du/dy)


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BENDALIR NEWTONIANBENDALIR NEWTONIAN

Bendalir yang memenuhi Hukum Kelikatan NewtonBendalir yang memenuhi Hukum Kelikatan Newton

== (du/dy)(du/dy)


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FAKTOR MEMPENGARUHIFAKTOR MEMPENGARUHI

KELIKATAN DALAM BENDALIRKELIKATAN DALAM BENDALIR Molekul bendalir diikat antara satu sama lain denganMolekul bendalir diikat antara satu sama lain dengan

daya ikatan molekul.daya ikatan molekul. Daya ikatan ini akan menyebabkan tegasan ricihDaya ikatan ini akan menyebabkan tegasan ricih

berlaku antara molekulberlaku antara molekul--molekul bendalir.molekul bendalir.

pa a su u men ng at, atan antara mo e upa a su u men ng at, atan antara mo e umenjadi lemah dan seterusnya menyebabkan tegasanmenjadi lemah dan seterusnya menyebabkan tegasanricih yang berlaku kurang.ricih yang berlaku kurang.

Perubahan pada tegasan ricih mempengaruhiPerubahan pada tegasan ricih mempengaruhikelikatan bendalirkelikatan bendalir


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CIRICIRI--CIRI BENDALIRCIRI BENDALIR

KetumpatanKetumpatan

Berat TentuBerat Tentu Ketumpatan BandinganKetumpatan Bandingan

Kelikatan KinematikKelikatan Kinematik

Tegangan PermukaanTegangan Permukaan

Tekanan Kapilari / Kesan RerambutTekanan Kapilari / Kesan Rerambut


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KETUMPATAN

DefinasiDefinasi :: jisim per unit isipadujisim per unit isipadu

SimbolSimbol ::

FormulaFormula :: = m/V= m/V

--

ContohContoh

AirAir :: 1000 kgm1000 kgm--33

RaksaRaksa :: 13546 kgm13546 kgm--33

UdaraUdara :: 1.23 kgm1.23 kgm--33

Minyak ParafinMinyak Parafin :: 800 kgm800 kgm--33


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Berubah mengikut jenis bendalirBerubah mengikut jenis bendalir

Untuk cecair, suhu dan tekanan hanyaUntuk cecair, suhu dan tekanan hanyamemberi kesan kecil pada pada ketumpatanmemberi kesan kecil pada pada ketumpatan

KETUMPATAN (samb.)

. .


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BERAT TENTU

DefinasiDefinasi :: berat per unit isipaduberat per unit isipadu

SimbolSimbol :: FormulaFormula :: == gg

UnitUnit :: k mk m--22ss--22

ContohContohAirAir :: 9814 kgm9814 kgm--22ss--22

RaksaRaksa :: 132943 kgm132943 kgm--22ss--22

UdaraUdara :: 12.07 kgm12.07 kgm--22ss--22Minyak ParafinMinyak Parafin :: 7851 kgm7851 kgm--22ss--22


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KETUMPATAN BANDINGAN

DefinasiDefinasi :: nisbah ketumpatan bendalirnisbah ketumpatan bendalir

dibandingkan dengandibandingkan denganketumpatan air pada suhuketumpatan air pada suhutertentu (4 darjah Celsius)tertentu (4 darjah Celsius)

SimbolSimbol :: SGSG FormulaFormula :: SG =SG = bb// H2O@4CH2O@4C UnitUnit :: tiadatiada

ContohContoh

AirAir :: 11

RaksaRaksa :: 13.513.5

UdaraUdara :: 1.23 x 101.23 x 10--33

Minyak ParafinMinyak Parafin :: 0.80.8


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KELIKATAN DINAMIK

DefinasiDefinasi :: daya ricih per unit luasdaya ricih per unit luas

SimbolSimbol :: FormulaFormula :: == / (du/dy)/ (du/dy)

UnitUnit :: k mk m--11ss--11

ContohContohAirAir :: 1.14 x 101.14 x 10--33 kgmkgm--11ss--11

RaksaRaksa :: 1.552 kgm1.552 kgm--11ss--11

UdaraUdara :: 1.78 x 101.78 x 10--55 kgmkgm--11ss--11

Minyak ParafinMinyak Parafin :: 1.9 kgm1.9 kgm--11ss--11


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KELIKATAN KINEMATIK

DefinasiDefinasi :: kelikatan dinamik per unit ketumpatankelikatan dinamik per unit ketumpatan

SimbolSimbol ::

FormulaFormula :: == //

--

ContohContoh

AirAir :: 1.14 x 101.14 x 10--66 mm22ss--11

RaksaRaksa :: 1.145 x 101.145 x 10--44 mm22ss--11

UdaraUdara :: 1.46 x 101.46 x 10--55 mm22 ss--11

Minyak ParafinMinyak Parafin :: 2.375 x 102.375 x 10--33 mm22ss--11


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TEGANGAN PEMUKAAN Ia disebabkan oleh daya antara molekulIa disebabkan oleh daya antara molekul--molekulmolekul

bendalir yang tidak stabil pada permukaan bendalirbendalir yang tidak stabil pada permukaan bendalir Ketidakseimbangan ini akan menyebabkanKetidakseimbangan ini akan menyebabkan

permukaan bendalir bertindak sebagai kulit ataupermukaan bendalir bertindak sebagai kulit atau

membranmembran Sifat ini boleh menyebabkan mata pisau cukurSifat ini boleh menyebabkan mata pisau cukur

terapung pada permukaan bendalirterapung pada permukaan bendalir


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TINDAKAN KAPILARI Ia juga disebabkan oleh daya antara molekulIa juga disebabkan oleh daya antara molekul--molekulmolekul

bendalir yang tidak stabil pada permukaan bendalirbendalir yang tidak stabil pada permukaan bendalir Ia akan menyebabkan permukaaan bendalir berbentukIa akan menyebabkan permukaaan bendalir berbentuk

cembung atau cekungcembung atau cekung


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CONTOH

Contoh 1Contoh 1

Contoh 2Contoh 2

Contoh 3Contoh 3

Contoh 4Contoh 4 Contoh 5Contoh 5

Contoh 6Contoh 6


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LATIHAN RujukRujuk

B. R Munson, D. F Young, T H. Okiishi, B. R Munson, D. F Young, T H. Okiishi, Fundamentals of Fluid Mechanics, JohnFundamentals of Fluid Mechanics, John

Wiley, 2002Wiley, 2002

Bab 1, mukasurat 32 & 33Bab 1, mukasurat 32 & 33

Soalan 1.24, 1.25, 1.28, 1.32 & 1.40Soalan 1.24, 1.25, 1.28, 1.32 & 1.40


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JAWAPANJAWAPAN

1.241.24

1.251.25

1.281.28

1.321.32 1.401.40


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Video 1Video 1 -- VISCOUS FLUIDSVISCOUS FLUIDSThe behavior of a flowing fluid depends on variousThe behavior of a flowing fluid depends on various

fluid properties. Viscosity, one of the importantfluid properties. Viscosity, one of the important

properties, is responsible forproperties, is responsible forthe shear force produced in a moving fluid.the shear force produced in a moving fluid.

Although the two fluids shown look alike (both are clearAlthough the two fluids shown look alike (both are clearliquids and have a specific gravity of 1), they behaveliquids and have a specific gravity of 1), they behave

very differentlyvery differently

when set into motion. The very viscous silicone oil iswhen set into motion. The very viscous silicone oil isapproximately 10,000 times more viscous than theapproximately 10,000 times more viscous than the

water.water.


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Video 2 - NO-SLIP CONDITIONAs a fluid flows near a solid surface, it "sticks" to theAs a fluid flows near a solid surface, it "sticks" to the

surface, i.e., the fluid matches the velocity of thesurface, i.e., the fluid matches the velocity of thesurface. This sosurface. This so--called "nocalled "no--slip" condition is a veryslip" condition is a veryimportant one that must be satisfied in any accurateimportant one that must be satisfied in any accurate

analysis of fluid flow phenomena.analysis of fluid flow phenomena.

Dye injected at the bottom of a channel through whichDye injected at the bottom of a channel through whichwater is flowing forms a stagnant layer near thewater is flowing forms a stagnant layer near thebottom due to the no slip condition. As the dyebottom due to the no slip condition. As the dye

filament is movedfilament is movedaway from the bottom, the motion of water is clearlyaway from the bottom, the motion of water is clearly

apparent. A significant velocity gradient is createdapparent. A significant velocity gradient is creatednear the bottom.near the bottom.

Vid 3 CAPILLARY TUBE


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Video 3 - CAPILLARY TUBE

VISCOMETER

Most devices (called viscometers) used to determineMost devices (called viscometers) used to determine

viscosity do not measure it directly, but insteadviscosity do not measure it directly, but insteadmeasure some characteristic with a knownmeasure some characteristic with a knownrelationship to viscosity.relationship to viscosity.

The capillary tube viscometer involves the laminar flowThe capillary tube viscometer involves the laminar flowof a fixed volume of fluid through a capillary tube.of a fixed volume of fluid through a capillary tube.The time required for the fluid to pass through theThe time required for the fluid to pass through the

tube is a measure of the kinematic viscosity of thetube is a measure of the kinematic viscosity of thefluid. As shown with the four tubes, the drain timesfluid. As shown with the four tubes, the drain timescan vary depending on the viscosity of the fluid andcan vary depending on the viscosity of the fluid and

the diameter of the capillary tube.the diameter of the capillary tube.

Vid 4 NON NEWTONIAN


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Video 4 - NON-NEWTONIAN

BEHAVIORFluids for which shearing stress is not linearly related toFluids for which shearing stress is not linearly related to

the rate of shearing strain are designated as nonthe rate of shearing strain are designated as non--Newtonian fluids.Newtonian fluids.

m xture o water an corn starc , w en p ace on am xture o water an corn starc , w en p ace on aflat surface, flows as a thick, viscous fluid. However,flat surface, flows as a thick, viscous fluid. However,when the mixture is rapidly disturbed, it appears towhen the mixture is rapidly disturbed, it appears to

fracture and behave more like a solid. The mixture isfracture and behave more like a solid. The mixture is

a nona non--Newtonian shear thickening fluid whichNewtonian shear thickening fluid whichbecomes more viscous as the shearing rate isbecomes more viscous as the shearing rate is

suddenly increased through the rapid action of thesuddenly increased through the rapid action of thespoon.spoon.

Vid 5 FLOATING RAZOR


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Video 5 - FLOATING RAZOR

BLADE

Surface tension forces exist at liquid/gas or liquid/solidSurface tension forces exist at liquid/gas or liquid/solid

interfaces. Although these forces are relatively small,interfaces. Although these forces are relatively small,they are quite important in many situations.they are quite important in many situations.

A heavierA heavier--thanthan--water, doublewater, double--edged steel razor bladeedged steel razor bladecan float on water. Without surface tension, the bladecan float on water. Without surface tension, the blade

would sink because its weight is greater than itswould sink because its weight is greater than itsbuoyant force.buoyant force.

However, surface tension forces are not large enough toHowever, surface tension forces are not large enough tosupport a slightly heavier single edged blade.support a slightly heavier single edged blade.


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