Dbs1012 Chapter 1 Physical Quantities And Measurement 5j68y
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
1.0: PHYSICAL QUANTITIES AND MEASUREMENT 1.1 : Understand the Physical Quantities.
At the end of this lesson, students should be able to: Describe physical quantities, base quantities, derived quantities and the International System (SI) of units. Define scalar and vector quantities. Solve problems of unit conversion.
Physical Quantities Physical Quantities are measurable and have physical (feel, see…) meaning. A physical quantity is a quantity that can be measured.
Numerical values and units give quantities meaning. There are many units for each quantities Example - Length: metres, centimetres, kilometres, feet, inches, miles, nautical miles, light year Only one of the many is an SI unit Quantity
SI Unit
Symbol
Length
Metre
m
Mass
Kilogram
kg
Time
Second
s
Temperature
Kelvin
K
UNIT SAINS JMSK PUO/JUN 2014
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
SI units for some other quantities. Quantites
Unit
speed
m/s
area
m2
volume
m3
density
kg/m 3
Only quantities that have the same units can be added or subtracted. Example 400 cm3 of water is added to 1 litre of water. How much water is there? Incorrect: 400 + 1 = 401cm3 Correct: 1 litre = 1000cm3 400 + 1000 = 1400 cm3 Prefixes Prefixes may be added to very small quantities. Very small numbers may have prefixes to make writing them easier. Example: 2 000 000 000 Byte = 2 GByte 0.000045 m = 45 m Prefixes are the preceding factor used to represent very small and very large physical quantities in SI units. Prefix
Abbreviation
Tera
T
x 1012
Giga
G
x 109
Mega
M
x 106
Kilo
K
x 103
deci
d
x 10-1
centi
c
x 10-2
milli
m
x 10-3
micro
µ
x 10-6
nano
n
x 10-9
UNIT SAINS JMSK PUO/JUN 2014
Power
Page 2
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Base Quantities 1. A base quantity is a physical quantity that cannot be derived from other physical quantities. Example: length, mass, time. 2. The base quantities and their respective units as well as the symbols used to represent them are shown in Table 1.
Base Quantities
SI Unit
Symbol of Unit
Length, l
meter
m
Mass, m
kilogram
kg
Time, t
second
s
electric current, Q
ampere
A
Temperature, T
kelvin
K
Table 1 Derived Quantities Derived quantities are physical quantities that are derived from the combinations of base quantities through multiplication or division or both these operations. Examples
(Speed is derived from dividing distance by time.) Example: Which of following is a derived quantity? Length / Mass / Weight /Temperature/Density/Heat
UNIT SAINS JMSK PUO/JUN 2014
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Example: State the physical quantity that can be measured by the following equipments: a) voltmeter b) thermometer c) ammeter d) balance. Derived Unit The derived unit is a combination of base units through multiplying and/or dividing them.
Example 1 Find the derived unit of density. Answer
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Scalar and Vector Quantity A scalar quantity is a quantity that has magnitude, but no direction. A vector quantity is a quantity that has both magnitude and direction.
Scalars
Vectors
distance
displacement
speed
velocity
mass
weight
time
acceleration
pressure
force
energy
momentum
Conversion of units Area and Volume
UNIT SAINS JMSK PUO/JUN 2014
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Example 1 Convert the unit of length, area and volume below to the units given. a) 7.2 m = ____________cm b) 0.32 m2 = ____________cm2 c) 0.0012 m3 = ____________cm3 d) 5.6 cm = ____________m e) 350 cm2 = ____________m2 f) 45000 cm3 = ____________m3 Answer a) 7.2 m = 7.2 x 102 cm b) 0.32 m2 = 0.32 x 104 cm2 = 3.2 x 103 cm2 c) 0.0012 m3 = 0.0012 x 106 cm3 = 1.2 x 103 cm3 d) 5.6 cm = 5.6 x 10-2 m e) 350 cm2 = 350 x 10-4 m2 = 3.5 x 10-2 m2 f) 45000 cm3 = 45000 x 10-6 m3 = 4.5 x 10-2 m3 Example 2 Change the following quantities to the units shown. a) 1 cm3 = ……… m3 , b) 13.6 g cm-3 = …….kg m-3 -1 -1 c) 72 km h = ….m s d) 15 ms-1 = …….kmh-1 Solution a) 1 cm3 = 1 cm x 1 cm x 1cm = 10-2 m x 10-2 m x 10-2 m = 10-6 m3 b) 13.6 gcm3 = 13.6g/1cm3 = (13.6 g x 10-3 kg)/( 10-6m3 ) =13.6 x 103 kg m-3 = 1.36 x 104 kg m-3 -1 c) 72 km h = 72 km/1h = (72 x 1000 m)/(60 x 60 s) = 20 m s-1 -1 d) 15 ms = …….kmh-1 = (15 x 10-3) / (1/3600) = 54kmh-1
Practices: Convert the following quantities to the units shown: a) 29 km to mm b) 600mm to cm c) 800 cm3 to m3 d) 60kmh-1 to ms-1 e) 10ms-1 to kmh-1 f) 3000kgm-3 to gcm-3 g) 2.84 gcm-3 to kgm-3
UNIT SAINS JMSK PUO/JUN 2014
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
1.2 : Analyse Data Of Measurement
At the end of this lesson, students should be able to: How to read and use Micrometer screw gauge, Vernier Calliper and meter rule . Describe inaccuracy and errors in measurement.
Measuring Instruments Metre rule The smallest division on a metre rule is 0.1 cm. A metre rule can therefore measure length accurately up to 0.1 cm only.
Figure 1: Meter Ruler Example calculation: Figure 2 shows the measurement of the length of a wooden block with ruler. a) State the accuracy of the ruler. b) Why the zero mark on the ruler not used as the origin of the measurement? c) State the category of error that must be avoided when reading the scale. d) What is the length of the wooden block?
Figure 2 Answer:
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
The Vernier Caliper This instrument may be used to measure outer dimensions of objects (using the main jaws), inside dimensions (using the smaller jaws at the top), and depths (using the stem).
How to read and use the Vernier Caliper?
The reading here is 3.7 mm or 0.37 cm.
UNIT SAINS JMSK PUO/JUN 2014
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
In figure above, the first significant figures are taken as the main scale reading to the left of the vernier zero, i.e. 3.4 cm. The remaining digit is taken from the vernier scale reading that lines up with any main scale reading, (i.e. 0.60 mm or 0.060 cm) on the vernier scale. Therefore the reading is 3.460 cm. EXERCISE:
Answer: 3.090 cm
UNIT SAINS JMSK PUO/JUN 2014
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Answer: 0.810 cm
MICROMETER A micrometer allows a measurement of the size of a body. It is one of the most accurate mechanical devices in common use. The micrometer screw gauge can be used to measure very small lengths such as the diameter of a wire or the thickness of a piece of paper as it can measure length accurately up to 0.01 mm.
Figure 5: Micrometer Screw Gauge
UNIT SAINS JMSK PUO/JUN 2014
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
7.5+0.000 = 7.500 mm
8.000 mm + 0.120 mm = 8.120 mm
UNIT SAINS JMSK PUO/JUN 2014
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
8.500 mm + 0.124 mm = 8.624
mm Depending on your eyes and screen resolution, you might be fairly confident that the reading is less than, say, 8.627 mm and similarly confident that it is greater than 8.621 mm. Thus you might assign a Reading Error to this measurement of 0.003 mm So, we would report the distance as 8.624 ± 0.003 mm. EXERCISE:
Answer: 7.880 mm
Answer: 3.090 mm
UNIT SAINS JMSK PUO/JUN 2014
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Answer: 5.801 ± 0.003 mm Inaccuracy and errors in measurement. Consistency The consistency of a measuring instrument is its ability to the same reading when a measurement is repeated. A set of measurements are consistent if all the values are close to the mean value. a) b) c)
The consistency of a measuring instrument can be improved by eliminating parallax errors during measurement. exercising greater care and effort when taking readings. using an instrument which is not defective.
Accuracy Accuracy is the degree of how close a measured value is to the actual (true) value. Precision is how close the measured values are to each other. Ways to improve the accuracy of a measurement: a) Repeated readings are taken and the average value is calculated. b) Avoid parallax errors. c) Avoid zero errors. d) Use measuring instruments with a higher accuracy. Examples of Precision and Accuracy:
Low Accuracy High Precision
UNIT SAINS JMSK PUO/JUN 2014
High Accuracy Low Precision
High Accuracy High Precision
Page 13
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Sensitivity The sensitivity of a measuring instrument is its ability to respond quickly to a small change in the value of a measurement. A measuring instrument that has a scale with smaller division is more sensitive. ERROR An error is defined as: "The difference between the measured value and the actual value." If two persons use the same instrument for measurement for finding the same measurement, it is not essential that they may get the same results. There may arise a difference between their measurements. This difference is referred to as an "ERROR". Types Of Error Errors can be divided into three categories: (1) Personal Error (2) Systematic Error (3) Random Error Personal Error An error comes into play because of faulty procedure adopted by the observer is called "PERSONAL ERROR". Personal error comes into existence due to making an error in reading a scale. It is due to faulty procedure adopted by the person making measurement. A parallax error is an error in reading an instrument due to the eye of the observer and pointer are not in a line perpendicular to the plane of the scale. Parallax errors are considered systematic errors. (*Systematic errors are those you can improve on. A parallax error can be corrected by you). Systematic Error The type of error arises due to defect in the measuring device is known as "SYSTEMATIC ERROR" Generally it is called "ZERO ERROR". it may be positive or negative error. Systematic error can be removed by correcting measurement device. Random Error The error produced due to sudden change in experimental conditions is called "RANDOM ERROR". For example: During sudden change in temperature, change in humidity, fluctuation in potential difference(voltage). It is an accidental error and is beyond the control of the person making measurement.
UNIT SAINS JMSK PUO/JUN 2014
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PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Minimum requirement assessment task for this topic: 1 Quiz & 1 Lab work Specification of quiz: CLO1- C3 , Specification of theoretical exercise: CLO3- C3, Specification of lab work: CLO2 – (P2,A2) ************************************************************************************************************** COURSE LEARNING OUTCOME (CLO) Upon completion of this topic, students should be able to: 1. solve the basic engineering science problems by using related concept. (C3) 2. organize appropriate experiments to prove related physic principles (P2),(A2) 3. apply related physic principles in various situations to enhance knowledge (C3)
AKTIVITI PELAJAR (JIGSAW METHOD) TUJUAN (OBJECTIVE): By the end of this lesson, the students should be able to: Define physical quantities, base quantities and derived quantities. List base quantities and their unit. List derived quantities and their unit. Convert the quantities unit. BAHAN AKTIVITI: SKIL 1 : Physical Quantities, SI unit and Prefixes. SKIL 2 : Base Quantities, SI unit and symbol. SKIL 3 : Derived Quantities and unit conversion. (Bahan boleh dirujuk dari nota atau rujukan lain) LANGKAH-LANGKAH: 1. Pelajar dibahagikan kepada 3 orang dalam satu kumpulan. Kumpulan ini dipanggil ‘Original Group’ 2. Setiap pelajar dalam satu kumpulan akan mendapat bahan aktiviti dari skil yang berbeza. 3. Pelajar diberi masa untuk mencari bahan dan berbincang. (Agihan akan diberi sebelum aktiviti sebenar yang akan dijalankan pada kelas berikutnya). 4. Pada hari aktiviti, pelajar duduk dalam kumpulan ‘Original Group’ masing-masing. 5. Kemudiannya pelajar yang mempunyai bahan pada skill yang sama akan digabungkan dalam satu kumpulan. Maka terbentuk tiga kumpulan yang dikenali sebagai ‘Expert Group’. Beri masa yang sesuai untuk perbincangan. Pensyarah boleh memberi input tambahan dan menjawab pertanyaan atau membuat pertanyaan. 6. Setelah selesai, pelajar akan kembali ke kumpulan masing-masing. Pelajar dari setiap skil yang akan mengajarkan apa yang diperbincangkan tadi kepada pelajar lain di dalam kumpulannya. Berikan masa yang sesuai. 7. Setelah selesai perbincangan tersebut, setiap pelajar akan menjawab satu soalan penilaian. Penilaian ini perlu untuk mengenalpasti semua pelajar telah mencapai objektif P&P pada hari tersebut. Soalan penilaian adalah berbentuk soalan pendek. Setiap pensyarah bebas menyediakan soalan masing-masing yang dapat menguji pelajar untuk mencapai objektif diatas.
UNIT SAINS JMSK PUO/JUN 2014
Page 15
DBS1012- ENGINEERING SCIENCE
1.0: PHYSICAL QUANTITIES AND MEASUREMENT 1.1 : Understand the Physical Quantities.
At the end of this lesson, students should be able to: Describe physical quantities, base quantities, derived quantities and the International System (SI) of units. Define scalar and vector quantities. Solve problems of unit conversion.
Physical Quantities Physical Quantities are measurable and have physical (feel, see…) meaning. A physical quantity is a quantity that can be measured.
Numerical values and units give quantities meaning. There are many units for each quantities Example - Length: metres, centimetres, kilometres, feet, inches, miles, nautical miles, light year Only one of the many is an SI unit Quantity
SI Unit
Symbol
Length
Metre
m
Mass
Kilogram
kg
Time
Second
s
Temperature
Kelvin
K
UNIT SAINS JMSK PUO/JUN 2014
Page 1
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
SI units for some other quantities. Quantites
Unit
speed
m/s
area
m2
volume
m3
density
kg/m 3
Only quantities that have the same units can be added or subtracted. Example 400 cm3 of water is added to 1 litre of water. How much water is there? Incorrect: 400 + 1 = 401cm3 Correct: 1 litre = 1000cm3 400 + 1000 = 1400 cm3 Prefixes Prefixes may be added to very small quantities. Very small numbers may have prefixes to make writing them easier. Example: 2 000 000 000 Byte = 2 GByte 0.000045 m = 45 m Prefixes are the preceding factor used to represent very small and very large physical quantities in SI units. Prefix
Abbreviation
Tera
T
x 1012
Giga
G
x 109
Mega
M
x 106
Kilo
K
x 103
deci
d
x 10-1
centi
c
x 10-2
milli
m
x 10-3
micro
µ
x 10-6
nano
n
x 10-9
UNIT SAINS JMSK PUO/JUN 2014
Power
Page 2
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Base Quantities 1. A base quantity is a physical quantity that cannot be derived from other physical quantities. Example: length, mass, time. 2. The base quantities and their respective units as well as the symbols used to represent them are shown in Table 1.
Base Quantities
SI Unit
Symbol of Unit
Length, l
meter
m
Mass, m
kilogram
kg
Time, t
second
s
electric current, Q
ampere
A
Temperature, T
kelvin
K
Table 1 Derived Quantities Derived quantities are physical quantities that are derived from the combinations of base quantities through multiplication or division or both these operations. Examples
(Speed is derived from dividing distance by time.) Example: Which of following is a derived quantity? Length / Mass / Weight /Temperature/Density/Heat
UNIT SAINS JMSK PUO/JUN 2014
Page 3
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Example: State the physical quantity that can be measured by the following equipments: a) voltmeter b) thermometer c) ammeter d) balance. Derived Unit The derived unit is a combination of base units through multiplying and/or dividing them.
Example 1 Find the derived unit of density. Answer
UNIT SAINS JMSK PUO/JUN 2014
Page 4
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Scalar and Vector Quantity A scalar quantity is a quantity that has magnitude, but no direction. A vector quantity is a quantity that has both magnitude and direction.
Scalars
Vectors
distance
displacement
speed
velocity
mass
weight
time
acceleration
pressure
force
energy
momentum
Conversion of units Area and Volume
UNIT SAINS JMSK PUO/JUN 2014
Page 5
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Example 1 Convert the unit of length, area and volume below to the units given. a) 7.2 m = ____________cm b) 0.32 m2 = ____________cm2 c) 0.0012 m3 = ____________cm3 d) 5.6 cm = ____________m e) 350 cm2 = ____________m2 f) 45000 cm3 = ____________m3 Answer a) 7.2 m = 7.2 x 102 cm b) 0.32 m2 = 0.32 x 104 cm2 = 3.2 x 103 cm2 c) 0.0012 m3 = 0.0012 x 106 cm3 = 1.2 x 103 cm3 d) 5.6 cm = 5.6 x 10-2 m e) 350 cm2 = 350 x 10-4 m2 = 3.5 x 10-2 m2 f) 45000 cm3 = 45000 x 10-6 m3 = 4.5 x 10-2 m3 Example 2 Change the following quantities to the units shown. a) 1 cm3 = ……… m3 , b) 13.6 g cm-3 = …….kg m-3 -1 -1 c) 72 km h = ….m s d) 15 ms-1 = …….kmh-1 Solution a) 1 cm3 = 1 cm x 1 cm x 1cm = 10-2 m x 10-2 m x 10-2 m = 10-6 m3 b) 13.6 gcm3 = 13.6g/1cm3 = (13.6 g x 10-3 kg)/( 10-6m3 ) =13.6 x 103 kg m-3 = 1.36 x 104 kg m-3 -1 c) 72 km h = 72 km/1h = (72 x 1000 m)/(60 x 60 s) = 20 m s-1 -1 d) 15 ms = …….kmh-1 = (15 x 10-3) / (1/3600) = 54kmh-1
Practices: Convert the following quantities to the units shown: a) 29 km to mm b) 600mm to cm c) 800 cm3 to m3 d) 60kmh-1 to ms-1 e) 10ms-1 to kmh-1 f) 3000kgm-3 to gcm-3 g) 2.84 gcm-3 to kgm-3
UNIT SAINS JMSK PUO/JUN 2014
Page 6
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
1.2 : Analyse Data Of Measurement
At the end of this lesson, students should be able to: How to read and use Micrometer screw gauge, Vernier Calliper and meter rule . Describe inaccuracy and errors in measurement.
Measuring Instruments Metre rule The smallest division on a metre rule is 0.1 cm. A metre rule can therefore measure length accurately up to 0.1 cm only.
Figure 1: Meter Ruler Example calculation: Figure 2 shows the measurement of the length of a wooden block with ruler. a) State the accuracy of the ruler. b) Why the zero mark on the ruler not used as the origin of the measurement? c) State the category of error that must be avoided when reading the scale. d) What is the length of the wooden block?
Figure 2 Answer:
UNIT SAINS JMSK PUO/JUN 2014
Page 7
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
The Vernier Caliper This instrument may be used to measure outer dimensions of objects (using the main jaws), inside dimensions (using the smaller jaws at the top), and depths (using the stem).
How to read and use the Vernier Caliper?
The reading here is 3.7 mm or 0.37 cm.
UNIT SAINS JMSK PUO/JUN 2014
Page 8
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
In figure above, the first significant figures are taken as the main scale reading to the left of the vernier zero, i.e. 3.4 cm. The remaining digit is taken from the vernier scale reading that lines up with any main scale reading, (i.e. 0.60 mm or 0.060 cm) on the vernier scale. Therefore the reading is 3.460 cm. EXERCISE:
Answer: 3.090 cm
UNIT SAINS JMSK PUO/JUN 2014
Page 9
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Answer: 0.810 cm
MICROMETER A micrometer allows a measurement of the size of a body. It is one of the most accurate mechanical devices in common use. The micrometer screw gauge can be used to measure very small lengths such as the diameter of a wire or the thickness of a piece of paper as it can measure length accurately up to 0.01 mm.
Figure 5: Micrometer Screw Gauge
UNIT SAINS JMSK PUO/JUN 2014
Page 10
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
7.5+0.000 = 7.500 mm
8.000 mm + 0.120 mm = 8.120 mm
UNIT SAINS JMSK PUO/JUN 2014
Page 11
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
8.500 mm + 0.124 mm = 8.624
mm Depending on your eyes and screen resolution, you might be fairly confident that the reading is less than, say, 8.627 mm and similarly confident that it is greater than 8.621 mm. Thus you might assign a Reading Error to this measurement of 0.003 mm So, we would report the distance as 8.624 ± 0.003 mm. EXERCISE:
Answer: 7.880 mm
Answer: 3.090 mm
UNIT SAINS JMSK PUO/JUN 2014
Page 12
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Answer: 5.801 ± 0.003 mm Inaccuracy and errors in measurement. Consistency The consistency of a measuring instrument is its ability to the same reading when a measurement is repeated. A set of measurements are consistent if all the values are close to the mean value. a) b) c)
The consistency of a measuring instrument can be improved by eliminating parallax errors during measurement. exercising greater care and effort when taking readings. using an instrument which is not defective.
Accuracy Accuracy is the degree of how close a measured value is to the actual (true) value. Precision is how close the measured values are to each other. Ways to improve the accuracy of a measurement: a) Repeated readings are taken and the average value is calculated. b) Avoid parallax errors. c) Avoid zero errors. d) Use measuring instruments with a higher accuracy. Examples of Precision and Accuracy:
Low Accuracy High Precision
UNIT SAINS JMSK PUO/JUN 2014
High Accuracy Low Precision
High Accuracy High Precision
Page 13
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Sensitivity The sensitivity of a measuring instrument is its ability to respond quickly to a small change in the value of a measurement. A measuring instrument that has a scale with smaller division is more sensitive. ERROR An error is defined as: "The difference between the measured value and the actual value." If two persons use the same instrument for measurement for finding the same measurement, it is not essential that they may get the same results. There may arise a difference between their measurements. This difference is referred to as an "ERROR". Types Of Error Errors can be divided into three categories: (1) Personal Error (2) Systematic Error (3) Random Error Personal Error An error comes into play because of faulty procedure adopted by the observer is called "PERSONAL ERROR". Personal error comes into existence due to making an error in reading a scale. It is due to faulty procedure adopted by the person making measurement. A parallax error is an error in reading an instrument due to the eye of the observer and pointer are not in a line perpendicular to the plane of the scale. Parallax errors are considered systematic errors. (*Systematic errors are those you can improve on. A parallax error can be corrected by you). Systematic Error The type of error arises due to defect in the measuring device is known as "SYSTEMATIC ERROR" Generally it is called "ZERO ERROR". it may be positive or negative error. Systematic error can be removed by correcting measurement device. Random Error The error produced due to sudden change in experimental conditions is called "RANDOM ERROR". For example: During sudden change in temperature, change in humidity, fluctuation in potential difference(voltage). It is an accidental error and is beyond the control of the person making measurement.
UNIT SAINS JMSK PUO/JUN 2014
Page 14
PHYSICAL QUANTITIES AND MEASUREMENT
DBS1012- ENGINEERING SCIENCE
Minimum requirement assessment task for this topic: 1 Quiz & 1 Lab work Specification of quiz: CLO1- C3 , Specification of theoretical exercise: CLO3- C3, Specification of lab work: CLO2 – (P2,A2) ************************************************************************************************************** COURSE LEARNING OUTCOME (CLO) Upon completion of this topic, students should be able to: 1. solve the basic engineering science problems by using related concept. (C3) 2. organize appropriate experiments to prove related physic principles (P2),(A2) 3. apply related physic principles in various situations to enhance knowledge (C3)
AKTIVITI PELAJAR (JIGSAW METHOD) TUJUAN (OBJECTIVE): By the end of this lesson, the students should be able to: Define physical quantities, base quantities and derived quantities. List base quantities and their unit. List derived quantities and their unit. Convert the quantities unit. BAHAN AKTIVITI: SKIL 1 : Physical Quantities, SI unit and Prefixes. SKIL 2 : Base Quantities, SI unit and symbol. SKIL 3 : Derived Quantities and unit conversion. (Bahan boleh dirujuk dari nota atau rujukan lain) LANGKAH-LANGKAH: 1. Pelajar dibahagikan kepada 3 orang dalam satu kumpulan. Kumpulan ini dipanggil ‘Original Group’ 2. Setiap pelajar dalam satu kumpulan akan mendapat bahan aktiviti dari skil yang berbeza. 3. Pelajar diberi masa untuk mencari bahan dan berbincang. (Agihan akan diberi sebelum aktiviti sebenar yang akan dijalankan pada kelas berikutnya). 4. Pada hari aktiviti, pelajar duduk dalam kumpulan ‘Original Group’ masing-masing. 5. Kemudiannya pelajar yang mempunyai bahan pada skill yang sama akan digabungkan dalam satu kumpulan. Maka terbentuk tiga kumpulan yang dikenali sebagai ‘Expert Group’. Beri masa yang sesuai untuk perbincangan. Pensyarah boleh memberi input tambahan dan menjawab pertanyaan atau membuat pertanyaan. 6. Setelah selesai, pelajar akan kembali ke kumpulan masing-masing. Pelajar dari setiap skil yang akan mengajarkan apa yang diperbincangkan tadi kepada pelajar lain di dalam kumpulannya. Berikan masa yang sesuai. 7. Setelah selesai perbincangan tersebut, setiap pelajar akan menjawab satu soalan penilaian. Penilaian ini perlu untuk mengenalpasti semua pelajar telah mencapai objektif P&P pada hari tersebut. Soalan penilaian adalah berbentuk soalan pendek. Setiap pensyarah bebas menyediakan soalan masing-masing yang dapat menguji pelajar untuk mencapai objektif diatas.
UNIT SAINS JMSK PUO/JUN 2014
Page 15
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