FORM 4: 1.2 UNDERSTANDING BASE QUANTITIES AND DERIVED QUANTITIES

THE MEANING OF PHYSICAL QUANTITY

A physical quantity is a physical characteristic that can be measured.

THE MEANING OF BASE QUANTITY

Base quantity is quantity that cannot be defined in terms of other base quantities.

BASE QUANTITY	QUANTITY SIMBOL	SI UNIT	UNIT SIMBOL
length	l	metre	m
mass	m	kilogram	kg
time	t	second	s
electric current	I	ampere	A
temperature	T	kelvin	K

THE MEANING OF DERIVED QUANTITY

A derived quantity is one which is obtained by combining base quantities by multiplication, division or both these operations.

PREFIXES

THE PURPOSE OF PREFIXES:to express some physical quantities those are either very big or very small

PREFIX	SYMBOL	VALUE
nano	n	10-9
micro	µ	10-6
milli	m	10-3
centi	c	10-2
deci	d	10-1
kilo	k	103
mega	M	106
giga	G	109

CONVERT OF UNITS

STANDARD FORM

A x 10ⁿ; where 1 ≤ A < 10 and n is an integer

EXPRESS NUMBER IN STANDARD FORM

i)                    0.0000002 m = 2.0 x 10^-7 m

ii)                   12760000 m = 1.276 x 10⁷ m