pdt 180 engineering science munira mohamed nazari school of bioprocess, unimap
TRANSCRIPT
PDT 180PDT 180ENGINEERING SCIENCEENGINEERING SCIENCE
MUNIRA MOHAMED NAZARI
SCHOOL OF BIOPROCESS, UNIMAP
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UNITS UNITS OF OF
MEASUREMENTMEASUREMENT
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TOPIC OUTLINETOPIC OUTLINE
• INTRODUCTION
• UNIT, STANDARDS & THE SI SYSTEM
• MEASUREMENT & UNCERTAINTY; SIGNIFICANT FIGURES
• CONVERTING UNITS
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Course outcome (co)Course outcome (co)
Ability to analyze problems related to units of measurements, and scalar and vector quantities.
CO 1
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INTRODUCTIONINTRODUCTION• Why we learn “Unit and Measurements”?
– First important aspect in any technical course study.
– As we always need to measure any quantity. For example, the length of the table.
– If we get the numerical value for the length of the table as 2, then we must compare that length relatively with a particular standard or unit.
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UNIT, STANDARDS & THE SI UNIT, STANDARDS & THE SI SYSTEM SYSTEM
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UNIT, STANDARDS & THE SI UNIT, STANDARDS & THE SI SYSTEMSYSTEM• UNIT
– The measurement of any quantity is made relative to a particular standard or unit and this unit must be specified along with the numerical value of the quantity.
– Unit used should always be stated.
• STANDARD UNITQuantity Standard Unit
Length Meter (m)
Time Second (s)
Mass Kilogram (kg)
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• SYSTEMS OF UNITS– Two types systems of units,
• English unit (inches, feet, or miles)• Metric unit (centimeters, meters, or kilometers)
– When dealing with the laws and equations of physics it is very important to use a consistent set of units.
– Today the most important is the Systeme International (SI).
– In SI units, the standard of length is meter, time is second and mass is kilogram.
HOWEVER…
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• BASE vs DERIVED UNITS– Physical quantities can be divided into two
categories;• Base quantities Base unit (single)• Derived quantities Derived unit
(multiple)
– SI Base Quantities and Units
Corresponding units
Corresponding units
Quantity Unit Unit Abbreviation
Length meter m
Time second s
Mass kilogram kg
Electric current ampere A
Temperature kelvin K
Amount of substance mole cd
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MEASUREMENT & MEASUREMENT & UNCERTAINTY; UNCERTAINTY;
SIGNIFICANT FIGURESSIGNIFICANT FIGURES
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• In the metric system, the larger and smaller units are defined in multiples of 10 from the standard or base unit.
• This is to makes calculation easier.• For example;
– 1 km = 1000 m, while 1 cm = 1/100 m @
• The prefixes “kilo-”, “centi-” and others can be applied to all units either base unit or derived unit.
• For examples;– A kilowtt (kW) is 1000 watt (W) and,– 1 milisecond (msec) is 1/1000 sec or
m 10 2
sec 10 3
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• Table below lists some of the Metric (SI) prefixed used in engineering and technical computation.
Prefixe Meaning As numbers Symbols
Kilo Thousand 1000 k
Mega Million 1 000 000 M
Giga Billion 1 000 000 000 G
Centi Hundredth 0.01 c
Mili Thousandth 0.001 m
Micro Milionth 0.000 001 µ
Nano Billionth 0. 000 000 001 n
10 2
103
10 3
10 6
10 9
109
106
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CONVERTING UNITSCONVERTING UNITS
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Conversion Factor
A ratio of equivalent values of a quantity expressed in different units.
A ratio of equivalent values of a quantity expressed in different units.
To convert a quantity expressed in terms of one unit to its equivalent in terms of another
unit by multiply the given quantity by the conversion factor (new unit/old unit).
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• Example:– To convert 36 mg to its equivalent unit in grams
(g).
– or
15
g 0.036 )mg 1000
g 1( ) 36( mg
36 mg 1 g 1000 mg
= 0.036 g Vertical line
Multiplication symbol
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• Example:– Convert an acceleration of 1 cm/s2 to its
equivalent in km/h2.
– Express the following sum using SI unit and with correct number of significant figures:
1.0 m + 14.25 cm + 1.24 x =
16
Answer = 129.6 km/h 2 Answer = 129.6 km/h 2
m 105
Answer = 1.2665 mAnswer = 1.2665 m
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Thank youThank you