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Solve the basic engineering science problems by using related concepts.

Organize an appropriate experiments to prove related physics principles.

Apply related physics principles in various situations to enhance knowledge.

ENGINEERING SCIENCE

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CHAPTER 1:

PHYSICAL QUANTITIES AND

MEASUREMENT

1.1 Understand the physical quantities

1.1.1 Describe base quantities, derived quantities and

the International System (SI) of units.

1.1.2 Define scalar and vector quantities.

1.1.3 Solve problems of unit conversion.

1.2 Interpret data of measurement

1.2.1 Describe inaccuracy and errors in measurement

1.2.2 Apply techniques for measurement to ensure

accurate data by using measurement

equipments:-

a. Ruler

b. Vernier Callipers

c. Micrometer Screw Gauge

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PHYSICAL

QUANTITIES &

MEASUREMENT PHYSICAL QUANTITIES

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PHYSICAL QUANTITIES

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PHYSICAL QUANTITIES

A quantity that can be measured.

A physical quantities have numerical

value and unit of measurement.

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PHYSICAL

QUANTITIES

BASE QUANTITIES

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BASE QUANTITIES

Base Quantities are physical quantities that cannot be derived from other physical quantities.

Scientific measurement using SI units (International System Units).

Base

Quantities

Symbol SI Unit Symbol of

SI unit

Length

l meter m

Mass m kilogram kg

Time t second s

Temperature T Kelvin K

Electric

current

I ampere A

Table 1.1 Shows five base quantities and their respective SI units

PHYSICAL

QUANTITIES

DERIVED QUANTITIES

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DERIVED QUANTITIIES

Derived Quantities are physical quantities derived from combination

of base quantities through multiplication or division or both

Derived Quantities Symbol Relationship with base quantities Derived units

Area A Length x Length m2

Volume V Length x Length x Length m3

Density Mass Length x Length x Length

kg/m3

Velocity v Displacement

Time

m/s

Acceleration a Velocity

Time

m/s2

Force F Mass x Acceleration N

Work W Force x Displacement J

Energy Ep Ek

Mass x gravity x high @

x mass x velocity x velocity

J

Power P Force x Displacement

Time

W

Pressure p Force

Area

N/m 2

Table 1.2 shows some of the derived quantities and their respective derived units

DERIVED QUANTITIES

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PHYSICAL QUANTITIES

BASE QUANTITIES

DEFINITION:

are physical quantities that

cannot be derived from

other physical quantities

EXAMPLES:

LENGTH

MASS

TIME

ELECTRIC CURRENT

TEMPERATURE

DERIVED QUANTITIES

DEFINITION

are physical quantities derived from combination

of base quantities through

multiplication or division or both

EXAMPLES:

AREA

VOLUME

DENSITY

FORCE

ECT

Quantity that can be measured

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PHYSICAL

QUANTITIES

SCALAR & VECTOR

QUANTITIES

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SCALAR AND VECTOR

QUANTITIES

SCALAR QUANTITIES

Physical quantities

which have size

(magnitude) but

without specified

direction.

VECTOR QUANTITIES

Physical quantities

which have size

(magnitude) and

specified direction.

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DIFFERENTIATION BETWEEN

SCALAR & VECTOR

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EXAMPLES OF

SCALAR QUANTITIES Mass

Time

Length

Temperature

Energy

Work

Speed

Pressure

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EXAMPLES OF

VECTOR

QUANTITIES

Displacement

Weight

Force

Velocity

Acceleration

Momentum

Activity

Tick () the right answer for physical quantities below

QUANTITY SCALAR

QUANTITY

VECTOR

QUANTITY

5 m

30 m/sec, East

5 m, North

20 degrees Celsius

256 bytes

PHYSICAL

QUANTITIES

PRIFIXES

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PREFIXES

Prefixes are used to simplify the

description of physical quantities that

are either very big or very small.

Prefix Symbol Value

tera T 1012

giga G 109

mega M 106

kilo k 103

hekto h 102

deka da 10

desi d 10-1

senti c 10-2

mili m 10-3

mikro H 10-6

nano n 10-9

piko P 10-12

Table 1.4 Lists some commonly used SI prefixes

UNIT MEASUREMENT

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CONVERSION UNITS

Example 1 :

Convert 3.5 kilometer to meter.

Solution

1km = 103m = 1000m

therefore

3.5 km = 3.5 km x 1000m

1 km

= 3.5 1000 m

= 3500 m

Illustrates the usage of prefixes

Example 2:

Express 0.0005 Mg in g

Solution

1kg = 103g = 1000g

1Mg = 106g = 1000 000g

therefore

0.005 Mg = 0.0005 Mg x 1000 000g

1 Mg

= 0.0005 1000 000 g

= 500 g

Convert the following into meters :

a. 12km

b. 6.32km

c. 12cm

d. 220cm

e. 212mm

f. 1234mm

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PHYSICAL

QUANTITIES

STANDART FORM

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STANDARD FORM

Standard form or scientific notation is used to express

magnitude in a simpler way. In scientific notation, a numerical

magnitude can be written as :

where 1 A < 10 and n is an integer

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STANDARD FORM

Example 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 UNITS Example 2:

Convert 60mm2 to m2 .

Solution

1 m = 1000 mm , 1m2 = 10002 m2

Therefore

60 mm2 x 1 m2 = 60 x 10-6 m2

10002 mm2

Contoh 3:

Convert 0.075 kW to mW.

Solution

kW W mW

Therefore

kW W = 0.075 kW 1000 W 1 kW

= 0.075 1000 W

= 75 W

W mW = 75 W 1000 mW 1 W

= 75 000 mW

Example 4 :

Change 60 km/j to m/s.

Solution 1 km = 1000m 60 km/j = 60 km x 1000 m x 1 hr 1 hour = 60 minute 1 hr 1 km 3600 s

1 minute = 60 sec = 60 x 1000 m

3600 s

= 16.67 m/s

Example 5 :

The density of pure water is 1000 kg m-3, what is its density in g cm-3 ?

Solution

1 kg = 1000 g

1 m = 100 cm

1000 kg = 1000 kg x 1000 g x ( 1 m x 1 m x 1 m )

m3 m3 1 kg 100 cm 100 cm 100 cm

= 1000 x 1000 g

1 00 00 00 cm3

= 1 g cm-3

EXERCISES 31

Convert the following into squares meters:

a. 2500cm

b. 22.2 cm

c. 600 mm

d. 21510 mm

Convert the

following into

cubic meters :

a. 5200 mm

b. 112345 mm

c. 55 cm

EXERCISES 32

Complete the following unit

conversion of speed.

i. 820 kmh-1 = __________ ms-1

ii. 1.36 ms-1 = __________ kmh-1

iii. 18.12 ms-1 = __________ kmh-1

iv. 970 kmh-1 = __________ ms-1

EXERCISES 33

Complete the following unit conversion of

density and pressure.

i. 7060 kgm-3 = __________ gcm-3

ii. 123000 kgm-3 = __________ gcm-3

iii. 2.45 gcm-3 = __________ kgm-3

iv. 39800 Nm-2 = __________ Ncm-2

v. 265x106 Nm-2 = __________ Ncm-2

Convert the following units

1. 120 cm in unit meter (m)

2. 550 mg in unit gram (g)

3. 9.81 m/s in unit km/h

4. 8500 cm2 in m2

5. 908 g/cm3 in kg/m3

6. 45 g/cm2 in kg/m2

MEASUREMENT

INSTRUMENT

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Micrometer screw gauge

Vernier calipers

MEASUREMENT INSTRUMENTS

Ruler

MEASUREMENT

VERNIER CALIPER

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38 VERNIER CALIPER

HOW TO USE VERNIER CALIPER

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HOW TO USE VERNIER CALIPER

1. 2.

3. 4

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10 + 6 0.25 + = 16.25mm

5.

HOW TO USE VANIER CALIPER

42 EXERCISES

MEASUREMENT

Micrometer Screw Gauge

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HOW TO USE MICROMETER SCREW GAUGE

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45 How to Read the Reading?

Reading = Reading of main scale +

Reading of thimble scale.

Reading of main scale = 0 - 25 mm

Reading of thimble scale = 0 - 0.49mm

Reading of main scale = 5.5mm

Reading of thimble scale = 0.28mm

Actual Reading = 5.5mm + 0.28mm =

5.78mm

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MEASUREMENT

ERROR IN MEASUREMENT

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ERROR IN MEASUREMENT

An error is the difference between the measured value and the actual value.

There 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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SYSTEMATIC ERRORS

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ZERO ERROR 51

RANDOM ERRORS

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BIBLIOGRAFI

http://spmphysics.onlinetuition.com.my/2

012/04/physical-quantities.html

www.youtube.com

Internet source

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