Quantities and Unit Conversions

l  Any measurement is always a multiple of some basic units.

(Ex. 5g = 1g × 5 ... 5g is a multiple of 1g)

l  Measurements can be described in a different unit.

(Ex. 1km = 1000m = 100000cm)

Quantities

Measurements have two parts- the number and the unit. Number and unit together= quantity. In Canada, we use SI (Système International) unit system to describe a measurement.

l SI System

　SI system is a French system, that dates back to the early 1800`s using power of 10.

lSI Base Units

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Measurement	Unit	Abbreviation
length	metre	m
time	second	s
mass	gram	g
amount of substance	mole	mol
luminous intensity	candela	cd
temperature	Kelvin	K
electric current	ampere	A

Conversions

When converting the two units, use “MAGIC ONE”!!!

l  Big　unit　to　small　unit　:

(original　measurement+its　unit)x
(power of 10 for measurement+　unit　converting　to)/（1+its　unit）

l  Ex. Converting 2Gg to g

　　

　　2Gg×10⁹g/1Gg = 2×10⁹g


l  Small　unit　to　big　unit:

(original　measurement+its　unit)x(1+unit converting into)/(power of 10 for measurement+original unit）

l  Ex. Converting 2ns to s

2ns×1s/10⁹ns= 2×10^-9s

Here is a video that talks more about measurements!