CHAPTER 3MEASUREMENTS

Where should you place your eyes during measure the length?

x x

USED OF SENSORY ORGAN AS MEASURING TOOLS

Mistake can easily occur

UNIT OF MEASUREMENTS

In order to measure the size of

measurement, we must have standard

definition of size

Unit

International System of Units (SI units)

Basic quantity

SI unit Symbol

Length Metre m

Mass Kilogramme kg

Time Second s

Temperature Kelvin K

Current Ampere A

1. MEASURING LENGTHS

Measuring tape

Ruler

Vernier callipers

Micrometer screw gauge

Internal & external callipers

SI unit of length is metre (m)

Larger unit of length is kilometre (km)

Smaller unit of length is centimetre (cm),

milimetre (mm) & micrometre (ɥm)

1km=1 000m 1m=100cm

1cm=10mm 1mm=1 000 ɥm

Petronas Twin Towers are 452m in height

PREFIXES IN LENGTH

2. MEASURING AREAS & VOLUMES

A) MEASURING AREA

Area = size of object’s surface

SI Unit = meter square, m2

1m

1m

Area = 1 m2

Formula of area measuring

Area of rectangle = length x

width

Area of circle = Π x radius2

Larger unit = kilometer square, km2

Smaller unit = centimeter square

(cm2) & millimeter square (mm2)

1km2 = 1000000m2

1m2 = 10000cm2

1cm2 = 100mm2

Land area of Malaysia is 330000km2

Area of irregular shape figure

Estimated by tracing figure onto

graph paper

Multiplying number of squares

covered

Square with more than half is

considered as one

B) MEASURING VOLUMES

Amount of space occupied

SI Unit = meter cube, m3

38.95m3

Correct position of eyes when reading a measuring cylinder

C. MEASURING MASS

Mass is amount of

matter in an object.

SI Unit = kilogramme, kg

Larger unit = tonne, t

Smaller unit = gramme, g &

milligramme, mg

1t = 1000kg 1kg = 1000g 1g =

1000mg

MEASURING TOOLS OF MASS

In shops & market

Electronic scale Platform scale

In laboratory or factory

Triple beam balance Lever balance

Physical balance

For more accurate reading

Analytical balance

D. MEASURING TEMPERATURE

Thermometer

Quantity used to express

degree of hotness or

coldness of an object

Measured using

thermometer

Mercury thermometer &

alcohol thermometer

SI unit of temperature is Kelvin,

K

Lowest temperature in universe

is -273oC (absolute zero, 0 K)

Kelvin temperature =

Celcius temperature + 273

Fahrenheit, 0F

Western countries

Freezing point of pure

water = 32 0F

Boiling point of pure water

= 212 0F

Fahrenheit temperature =

X Celsius temperature +

32

92

USING LIQUID-FILLED THERMOMETER IN

CORRECT WAY

???

CLINICAL THERMOMETER

Measure body temperature

Normal - 36.9oC

Highest – 42.0 oC

Mercury thermometer,

electronic thermometer

D. MEASURING TIME

SI Unit of time is second, s

Hour (h) & minute (m)

1 hour = 60 min 1min =

60s

METHODS OF TIME MEASUREMENTS

Sand clock Sundial

NOWADAYS

HOW TO USE STOPWATCH??

Complicated than normal

watch

Vary in structure, external

features & method of use

Mechanical stopwatch