# Metric System Presentation ```Announcements
Two Youtube videos are posted and a homework
Office Hours
Competency:
II -- Apply quantitative skills to represent and
communicate scientific concepts.
Skills:
Convert between units algebraically
Understand how to use the metric prefixes
Questions to think about during this lesson:
What is measurement?
Why do we use standard units of measurement?
What is the International System of Units?
What are the advantages of using the SI?
What are the SI units?
This topic is about measurement which can be an observation or
a description that includes a number and a unit.
Long time ago, people measured quantities in many different
ways which included using their bodies such as arms, feet and
steps. These systems had many problems such as that some
people do not have the same length of arm and feet.
Making standard measurements proves to work well because
someone at Abaarso can measure a quantity and another person
in Hargeisa can also measure the same quantity in the same
amount of Kilograms. Experiments must be repeatable to make
accurate results and standard units allow us to repeat other
scientists' experiments. The system of measurement that is best
suited to scientific purpose is the metric system.
The metric system was developed in France near the end of the
eighteenth century and it uses the decimal basis to convert one
metric to another. Because the metric system is multiples of ten,
calculation can greatly be simplified by moving the decimal
place.
The metric system that officially scientists use is called the
International System of Units which is SI Units in short. This
lesson is going to distinguish between the physical quantities
and units of measurement. All the things or the quantities that
are measurable in the universe such as length are known as
physical quantities. The units used to measure length, for
instance, is meter which is the metric unit of measurement. In
the table below, the seven fundamental units of measurement
are shown with the seven physical quantities they measure and
also their symbols for each physical quantity and SI Unit.
Physical Quantity
Physical Quantity
SI Unit
SI Unit
Name
Symbol
Name
Abbreviation
Length
l
metre
m
Mass
m
kilogram
kg
Time
t
second
s
Electric Current
I
ampere
A
Temperature
T
Kelvin
K
Amount of Substance
n
mole
mol
Luminous Intensity
l
candela
cd
Physical quantity
Physical quantity
SI Unit
SI unit
Name
Symbol
Abbreviation
Name
m2
area
A
volume
V
m3
cubic meter
frequency
f
Hz
Hertz
velocity
v
acceleration
a
m s –1
m s –2
square meter
meters per second
meters per second squared
force
F
N
Newton
pressure
P or p
Pa
Pascal
power
P
W
Watt
energy
E
J
Joule
voltage
V
V
Volt
resistance
R
Ω
Ohm
conductance
G
S
Siemens
charge
Q
C
Coulomb
```