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QB003 – SCIENCE (BRIDGING). CHAPTER 1: UNITS AND MEASUREMENT. UNDERSTANDING OF UNITS & MEASUREMENT. State the base quantity, derived quantity and its unit Express quantities using prefixes Express quantities using scientific notation Solve problems involving conversion of units - PowerPoint PPT Presentation
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QB003 – SCIENCEQB003 – SCIENCE(BRIDGING)(BRIDGING)
CHAPTER 1: CHAPTER 1: UNITS AND UNITS AND
MEASUREMENTMEASUREMENT
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UNDERSTANDING OF UNDERSTANDING OF UNITS & MEASUREMENTUNITS & MEASUREMENT
State the base quantity, derived quantity and its unitState the base quantity, derived quantity and its unit Express quantities using prefixesExpress quantities using prefixes Express quantities using scientific notationExpress quantities using scientific notation Solve problems involving conversion of unitsSolve problems involving conversion of units Measure physical quantities using appropriate Measure physical quantities using appropriate
equipmentsequipments Explain types of experimental errorsExplain types of experimental errors
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INTRODUCTION
Physical quantities
Base quantities Derived quantities
Prefixes Scientific notation(standard form
Scalar quantities Vector quantities
Measurement
Error
Systematic error Random error
CONCEPTUAL MAP
BASE QUANTITIESBASE QUANTITIES
Base QuantitiesBase Quantities are pare physical quantities that cannot be defined in term of hysical quantities that cannot be defined in term of other quantities.other quantities.
Scientific measurement using SI units (International System Units)Scientific measurement using SI units (International System Units). .
Base Base QuantitiesQuantities
SymbolSymbol SI UnitSI Unit Symbol of Symbol of
SI unitSI unit
LengthLength ll metermeter mm
MassMass mm kilogramkilogram kgkg
TimeTime tt secondsecond ss
TemperatureTemperature TT KelvinKelvin KK
Electric Electric currentcurrent
II ampereampere AA
Table 1.1 Shows five base quantities and their respective SI units
DERIVED QUANTITIIESDERIVED QUANTITIIES Derived QuantitiesDerived Quantities are physical quantities derived from combination are physical quantities derived from combination
of base quantities through multiplication or division or bothof base quantities through multiplication or division or both
Derived QuantitiesDerived Quantities SymbolSymbol Relationship with base quantitiesRelationship with base quantities Derived unitsDerived units
AreaArea AA Length x LengthLength x Length mm22
VolumeVolume VV Length x Length x LengthLength x Length x Length mm33
DensityDensity ρρ MassMassLength x Length x LengthLength x Length x Length
kg/mkg/m33
VelocityVelocity vv DisplacementDisplacementTimeTime
m/sm/s
AccelerationAcceleration aa VelocityVelocityTimeTime
m/sm/s22
ForceForce FF Mass x AccelerationMass x Acceleration NN
WorkWork WW Force x DisplacementForce x Displacement JJ
EnergyEnergy EEpp
EEkk
Mass x gravity x high @Mass x gravity x high @½ x mass x velocity x velocity½ x mass x velocity x velocity
JJ
PowerPower PP Force x DisplacementForce x DisplacementTimeTime
WW
PressurePressure p p ForceForceAreaArea
N/mN/m 2 2
Table 1.2 shows some of the derived quantities and their respective derived units
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Scalar Quantities & Vector QuantitiesScalar Quantities & Vector Quantities Scalar quantitiesScalar quantities are physical quantities that have are physical quantities that have magnitude onlymagnitude only Vector quantitiesVector quantities physical quantities that have physical quantities that have magnitudemagnitude and and
directiondirection
Scalar quantitiesScalar quantities Vector quantitiesVector quantities
LengthLength WorkWork DisplacementDisplacement
SpeedSpeed TemperatureTemperature VelocityVelocity
MassMass DensityDensity AccelerationAcceleration
TimeTime EnergyEnergy MomentumMomentum
AreaArea VolumeVolume ForceForce
Table 1.3 shows a list of some examples of scalar and vector quantities
PREFIXESPREFIXES
PrefixesPrefixes are used to simplify the are used to simplify the description of physical quantities that description of physical quantities that are either very big or very small.are either very big or very small.
PrefixPrefix SymbolSymbol ValueValue
teratera TT 10101212
gigagiga GG 101099
megamega MM 101066
kilokilo kk 101033
hektohekto hh 101022
dekadeka dada 1010
desidesi dd 1010-1-1
sentisenti cc 1010-2-2
milimili mm 1010-3-3
mikromikro HH 1010-6-6
nanonano nn 1010-9-9
pikopiko PP 1010-12-12
Table 1.4 Lists some commonly used SI prefixes
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STANDARD FORMSTANDARD FORMStandard formStandard form or or scientific notationscientific notation is used to express magnitude in is used to express magnitude in a simpler way. In scientific notation, a numerical magnitude can be a simpler way. In scientific notation, a numerical magnitude can be written as :written as :
A x 10A x 10nn,, where 1 where 1 ≤ A < 10 and ≤ A < 10 and nn is an integer is an integer
Example 1.1 :
For each of the following, express the magnitude using a scientific notation.(I) The mean radius of the balloon = 100 mm(II) The mass of a butterfly = 0.0004 kg
Solution:
The mean radius of the balloon= 100 mm= 1.0 x 102 mm
The mass of a butterfly= 0.0004 kg= 4.0 x 10-4 kg
CONVERSION UNITSCONVERSION UNITS
Example 1.2 Example 1.2 : :
Convert 3.5 kilometer to meter.Convert 3.5 kilometer to meter.
SolutionSolution1km = 101km = 1033m = 1000mm = 1000m
therefore therefore 3.5 km = 3.5 km 3.5 km = 3.5 km xx 1000m 1000m
1 km1 km = 3.5 = 3.5 1000 m 1000 m = = 3500 m3500 m
Illustrates the usage of prefixesIllustrates the usage of prefixes
Example 1.3Example 1.3::
Express 0.0005 Mg in gExpress 0.0005 Mg in g
SolutionSolution1kg = 101kg = 1033g = 1000gg = 1000g
1Mg = 101Mg = 1066g = 1000 000gg = 1000 000g
therefore therefore 0.005 Mg = 0.0005 Mg 0.005 Mg = 0.0005 Mg xx 1000 000g 1000 000g
1 Mg1 Mg = 0.0005 = 0.0005 1000 000 g 1000 000 g = = 500 g500 g
Example 1.4Example 1.4::
Change 50 msec to sec.Change 50 msec to sec.
SolutionSolution1 msec = 101 msec = 10-3-3 sec =0.001sec sec =0.001sec
ThereforeTherefore50 msec = 50 msec x 50 msec = 50 msec x 1 sec 1 sec
0.001 msec 0.001 msec = 50 x 1 sec= 50 x 1 sec 0.001 0.001 = 50 x 10= 50 x 10-3 -3 secsec = 50 x 10= 50 x 10-2 -2 secsec = = 0.05 sec0.05 sec
Contoh 1.5Contoh 1.5::
Convert 0.075 kW to mW.Convert 0.075 kW to mW.
SolutionSolution
kW → W → mWkW → W → mW
ThereforeTherefore
kW → W = 0.075 kW kW → W = 0.075 kW 1000 W 1000 W 1 1 kW kW = 0.075 = 0.075 1000 W 1000 W
= 75 W= 75 W
W W → → mW = 75 W mW = 75 W 1000 mW 1000 mW 1 W 1 W
= = 75 000 mW75 000 mW
CONVERSION UNITSCONVERSION UNITS
Example 1.6Example 1.6 : :
Change 60 km/j to m/s.Change 60 km/j to m/s.
SolutionSolution 1 km = 1000m1 km = 1000m 60 km/j = 60 km x 1000 m x 1 hr60 km/j = 60 km x 1000 m x 1 hr 1 hour = 60 minute1 hour = 60 minute 1 hr 1 km 3600 s 1 hr 1 km 3600 s 1 minute = 60 sec = 60 x 1000 m1 minute = 60 sec = 60 x 1000 m 3600 s3600 s
= = 16.67 m/s16.67 m/s
Example 1.7Example 1.7 : :
The density of pure water is 1000 kg mThe density of pure water is 1000 kg m-3-3, what is its density in g cm, what is its density in g cm-3 -3 ??
SolutionSolution 1 kg = 1000 g1 kg = 1000 g 1 m = 100 cm1 m = 100 cm
1000 kg = 1000 kg x 1000 g x ( 1 m x 1 m x 1 m )1000 kg = 1000 kg x 1000 g x ( 1 m x 1 m x 1 m ) mm33 m m33 1 kg 100 cm 100 cm 100 cm 1 kg 100 cm 100 cm 100 cm
= 1000 x 1000 g = 1000 x 1000 g 1 00 00 00 cm1 00 00 00 cm33
= 1 g cm= 1 g cm-3-3
EXERSICEEXERSICEConvert the following unitsConvert the following units
1.1. 120 cm in unit meter (m)120 cm in unit meter (m)
2.2. 550 mg in unit gram (g)550 mg in unit gram (g)
3.3. 5600 mV in KV5600 mV in KV
4.4. 9.81 m/s in unit km/j9.81 m/s in unit km/j
5.5. 8500 cm8500 cm22 in m in m22
6.6. 908 g/cm908 g/cm33 in kg/m in kg/m33
7.7. 45 g/cm45 g/cm22 in kg/m in kg/m22
Micrometer screw gaugeMicrometer screw gauge
Vernier calipersVernier calipers
MEASUREMENT INSTRUMENTS
RulerRuler
ERROR IN MEASUREMENTERROR IN MEASUREMENT An error is the difference between the measured value and the An error is the difference between the measured value and the
actual value.actual value. There are 2 main types of errors in measurementThere are 2 main types of errors in measurement
Systematic errors
• May be due to the error in calibration of instruments • Zero error is due to non-zero reading when the actual reading should be zero
Random errors
• Due to mistakes made by observer when taking measurement either through incorrect positioning of the eye (parallax) or the instruments when taking measurement
• It may also occur when there is a sudden change of environmental factors like temperature, air circulation and lighting
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