# Download 1.01 Numbers and units and 1.02 A system of units

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```Chapter 1
Measurement and
Units
 1.01
Numbers and units
 1.02 A system of units
 1.03 Measuring length and time
 1.04 Volume and density
 1.05 Measuring volume and density
 1.06 More about mass and velocity
1.01 Numbers and units
1.02 A system of units
Introduction to Physics

Physics is the study of natural phenomena
and properties of matter.
Light
Waves
Heat
Force and
motion
Field of study
in physics
Electricity and
electromagnetism
Electronics
Nuclear
Physics
1.01 Numbers and units

Physical quantities are
quantities that can be
measured.

The value of the
measurement consists
of a numerical
magnitude and a units.
Physical
Quantity
Base
Quantity
Derived
Quantity
Base Quantities
 Base
quantities are physical
quantities that cannot be defined in
term of others quantities.
 SI
 International System of Units
The seven base quantities
are
 Length
 Mass
 Temperature
 Time
 Electric
current
 Amount of substance
 Luminous intensity
Quantity
Unit
Symbol
Length
Meter
m
Mass
Kilogram
kg
Time
Second
s
Temperature
Kelvin
K
Current
Ampere
A
Amount of
substance
Luminous
intensity
Mole
mol
candela
cd

The five important base quantities:
Base Quantity Symbol
SI Unit
Length
l
Metre
Symbol of SI
unit
m
Mass
m
Kilogram
kg
Time
t
Second
s
Temperature
T
Kelvin
K
Current
I
Ampere
A
• Derived quantities are physical quantities derived
from combination of base quantities through
multiplication or division or both multiplication and
division.

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
Hecto
ha
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
Thanks God My Killer Husband Died During Christmas Makes Me Not Petrified
Standard form or scientific notation is used
to express magnitude in a simpler way.
 In scientific notation, a numerical
magnitude can be written as:

A x10n, where 1 ≤ A < 10 and n is an integer.
Examples
The distance between the Earth and the Sun
= 150 000 000 000 m
= 1.5 x 1011 m
Example 1
1.
0.00000008 m  ? m
= 8 x 10-8 m
2.
75 000 000 kg  ? kg
= 7.5 x 107 kg
3.
0.0007766 m  ? m
= 7.766 x 10-4 m
Example 2
1.
8 cm  ? m
= 8 x 10-2 m
2.
75 00 kg  g
= 7.5 x 103 x 103 g
= 7.5 x 106 g
3.
0.776 mm  ? m
= 7.76 x 10-1 x 10-3 m
= 7.76 x 10-4 m
Exercise 1
Exercise 2
Exercise 3
Exercise 4
1.
0.03 m  ? cm
2.
50 milliseconds  ? Seconds
3.
94.6 MHz  ? Hz
4. 1 000 000 mm  ? km
5. 0.0005 Mg  ? g
```
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