PHYSIC FORM 4 CHAPTER 1

PHYSICS

Chapter 1 :Introduction to Physics

1.1           Understanding Base Quantities and Derived           

                                                                              Quantities

1.   A physical quantity is a measureable quantity.

2.Base Quantities are physical quantities that cannot be   defined in terms of the other physical quantities.

3.The unit measurement of a base quantity is known as a base unit or SI unit.

Base quantity	Quantity Symbol	SI unit	Symbol
Lenght	l	metre	m
Mass	m	kilogram	kg
Time	t	second	s
Electric current	I	ampere	A
Temperature	T	kelvin	K

4. Derived quantities are physical quantities which are a combination of base quantities expressed as products or ratios.

Derived quantity	Express in derived quantity	Units
volume	l x l x l	m3
density		kgm−3
velocity		m s−1
force		N
Electric charge	l  t	C

5.  Standard form is a shorter method of expressing a very small or a

     very large number. The general standard form is written as:

A  x 10ⁿ 

where 1≤ A< 10 and ⁿ is an integer.

Hence, the distance between the Earth and the Sun

=150 000 000 000m

=1.5 x 10¹¹m

5.  Prefixes are used to represent physical quantities which  

have very large or small number values in SI units

Prefix	Symbol	Factor
Tera	T	1012
Giga	G	109
Mega	M	106
Kilo	k	103
Hecto	h	102
Deca	da	101
Deci	d	10-1
Centi	c	10-2
Milli	m	10-3
Micro	µ	10-6
Nano	n	10-9
Pico	p	10-12