Transcript 1.1 Imperial Measure

Introduction to the International
System of Units (SI) and the
Metric System
Mr. Tang and Mr. Pulickeel
SPH3U1
September 2008
In the beginning
 Back in the day (1000s of years ago) when
people built things themselves, it wasn’t
necessary to measure things because
everyone did it themselves.
I need a
bolt as
wide as
thumb
What you talkin’ ‘bout Willis?
 However, projects became more complicated, it became
necessary to have others work different parts, therefore they
had to standardize measurement.
moron
…
Sir, I don’t
know what your
thumb looks
like…
Birth of Imperialism
 So they decide to take the most popular guy,
measure his thumb and call it an inch. This
guy was the King!
An inch was the width of a thumb
A foot was the size of the kings
foot, which eventually became 12
inches.
A yard was the distance from the
tip of a man's nose to the end of
his outstretched arm. Eventually,
3 feet became a yard
Other systems
 The British empire used this method to devise measurements
for mass, volume and time. For instance a pound was equal to
7002 troy grains
 Other countries developed their own units of measure
7001? That’s
stupid! A
pound should
be 7002…
Your sands
are no match
for our
stones!
What’s a
troy grain?
We use
wheat
seeds
Sacre Bleu! C’est tres confusant!
 In 1586, the Flemish mathematician Simon Stevin
published a small pamphlet called De Thiende ("the
tenth").
 He thought counting by decimal fractions would be
really nifty! His idea was slow to catch on…
I also invented the
land yacht! It’s a
wagon with sails…
WEEEEE!
Vive Le France!
 Eventually (in the 1800s), the French adopted
the Metric System.
 In the 1970s many commonwealth (former
British colonies) switched to the metric
system.
SI Units of Measurement
 When working with numbers, it is necessary
to distinguish between the quantity and its
units
 Quantity describes something that has
magnitude, size or amount (mass, length,
etc...)
 Units is a quantity adopted as a standard of
measurement (kg, m, etc...)
The Super SI Seven!
Unit
Symbol
Quantity
kilogram
kg
mass
metre
m
length
second
s
time
ampere
A
electric current
kelvin
K
thermodynamic
temperature
mole
mol
amount of substance
candela
cd
luminous intensity
GRAMS!
• The gram was originally one millionth of the mass of a
cubic metre of water
• It is currently defined by one thousandth of the mass of a
specific Pt/Ir mass that is kept in a vault in France
• There are efforts underway to redefine it in terms of
physical quantities that could be reproduced in any
laboratory with suitable equipment.
• The SI unit is kg
METRE!
• The metre was defined as the length of a particular bar
of platinum-iridium alloy
• Then it was defined as 1⁄40 000 000 the earth’s circumference
• It was then defined as the wavelength of light emitted by
a specified atomic transition;
• It is now is defined as the distance travelled by light in
an absolute vacuum during 1⁄299,792,458 of a second
SECONDS!
• The second was originally 1⁄86,400 of the mean solar
day
• It was redefined in 1967 to be 9,192,631,770 periods of
vibration of the radiation emitted at a specific wavelength
by an atom of caesium-133
• There are plans to redefine it as something which can be
reproduced in any equipped lab
Temperature!
• The Celsius temperature was defined as a scale with
0°C being defined as its freezing point and 100°C being
defined as its boiling point at a pressure of one standard
atmosphere.
• SI unit is the Kelvin (K), a scale whose units have the
same "size", but which starts at absolute zero. Zero
degrees Celsius equals 273.15 K
• NOTE: ° is no longer to be used with Kelvins
Moles!
• A mole is the amount of a substance which contains as
many elementary entities as there are atoms in 12
grams of Carbon-12
• The currently accepted number of atoms in 12 grams of
Carbon-12 is 6.02214179×1023 atoms. This number is
called Avogadro's Constant
Moles!
• The relationship of the atomic mass unit (u) Avogadro's
number means that a mole can also be defined as: the
quantity of a substance whose mass in grams is the
same as its formula weight.
• For example, Iron (Fe) has a atomic mass of 55.84 u, so
a mole of iron has a mass of 55.845 grams. This
notation is very commonly used by chemists and
physicists.
Amperes and Candelas!
• An Ampere is a measure of Electrical Currents. We will
learn about this later on.
• A Candela is a measure of the power emitted by a light
source in a particular direction. A common candle emits
light with a luminous intensity of roughly one candela.
Imperial Systems
 Today, the entire world is metric, except for
the US, Myanmar and Liberia
Zut Alors!
 The French tried to implement Metric Time in
1794. They6 divided
thelater…
day into 10
 September
It was suspended
months
decimal hours. One decimal hour equaled 100
decimal minutes and each decimal minute equaled
100 decimal seconds
Counting Metric
The great thing about the metric system is that everything is counted by bases of 10!
Prefix
Power
Symbol
exa
1018
E
peta
1015
P
tera
1012
T
giga
109
G
mega
106
M
kilo
103
k
base unit
100
milli
10-3
m
micro
10-6
μ
nano
10-9
n
pico
10-12
p
femto
10-15
f
atto
10-18
a
Doing Conversions
(when considering Sig Fig)
Doing Conversions
Doing Conversions
Doing Conversions
1 m2 =
cm2
1100
m cm
100 cm
1m
2
100 x 100 = 10
000
cm
2
1m
If 1 yd = 3ft, then 4 yd2 =
ft2
1 yd
3ft
2 yd
6 ft
4 yd2
36 ft2
2 yd
6 ft
Doing Conversions
Word Problem
 John is driving 65 km/hr. Simon can run at a
speed of 9.2 m/s. Sam rides her bike at a rate
of 0.8 km/min. Who is faster?
What is the challenge to this problem?
Google “convert.exe”
www.JoshMadison.com  Select “Convert for Windows”