International System of Units
----- Metric ----Section 3.3
warmup

How many sig figs in:
1.
2.
3.
4.

0.003010 km
44.0 g/mole
190 miles to Houston from Dripping
1.61 kilometers = 1 mile
Do the calculation to the correct sig
figs.
6.
7.
44.0g + 1.778g =
190mi x 1.61km/mi =
objective
 to
3.3
list SI units of measurement
and common SI prefixes
 to convert metric units using
prefixes
Weights and Measures





Weights and measures were among the earliest human
inventions.
Length units were used for construction
Units of weight were need for trading goods.
When you make a measurement, you must assign the
correct units.
What is someone told you to “walk five in that
direction”?

Five what???? feet? meters? yards? miles?
The International System of Units
SI Units
All measurements need a reference standard
to compare to.
 The science community uses a revised system
of the metric system called:
 the International System of Units,
 abbreviated SI for the French name,
Le Systéme International d’Unités.

What system do modern scientists use for
measurement?
A.
B.
C.
Standard feet and inch system
International Metric System
International System of Units (SI units)
The International System of Units
SI Units
Quantity
SI Unit
Symbol
Non-SI Unit
Unit
Symbol
Length
Meter
m
-
-
Volume
Cubic meter
m3
Liter
L
Mass
Kilogram
kg
-
-
Temperature
Kelvin
K
Celsius
oC
Pressure
Pascal
Pa
Atmosphere
atm
Time
Second
s
-
-
Density
Grams per
milliliter
g/mL
-
-
Grams per
cubic centimeter
g/cm3
What is the SI unit for mass?
A.
B.
C.
D.
pound
mass
kilogram
gram
What is the SI unit for length?
A.
B.
C.
D.
foot
centimeter
meter
kilometer
Commonly used prefixes in the Metric
system


For very small or very large numbers, it’s not always convenient to
use the base SI unit.
Instead, we add a prefix.
Prefix
Symbol
Multiplier
Kilohectodeka-
k
h
da
decicentimillimicronano-
d
c
m
μ
n
1000
100
10
1
1/10
1/100
1/1000
1/1,000,000
1/1,000,000,000
Scientific
Notation
103
102
101
100
10-1
10-2
10-3
10-6
10-9
What is the multiplier for the prefix “kilo”?
A.
B.
C.
D.
10
100
1000
1/1000
Common Metric units of length
Unit
Symbol
relationship
example
kilometer
km
1 km = 1000 m
from DS High School to
DS middle school ~ 1 km
meter
m
base unit
height of doorknob from the
floor ~ 1 m
decimeter
dm
10 dm = 1 m
diameter of a large orange
~ 1 dm
centimeter
cm
100 cm = 1 m
width of a shirt button
~ 1 cm
millimeter
mm
1000 mm = 1 m
thickness of dime
~ 1 mm
How many centimeters in one meter?
A.
B.
C.
D.
E.
F.
1 / 1000
1 / 100
1 / 10
10
100
1000
If you had a 200cm long string, how many
meters would that be?
Mr. T’s first cell phone
Commonly used prefixes in the Metric
system

Example: Convert 205.61 centimeters to meters
How many meters in 1 kilometer?
How many meters is one millimeter (mm)?
A.
B.
C.
D.
E.
F.
1/1000
1/100
1/10
10
100
1000
Example: Convert 10 kilometers into
millimeters:

10km = ? mm
Common Metric units of volume
Unit
Symbol
relationship
example
Liter
L
base unit
2 water bottles = 1 L
milliliter
mL
1000 mL = 1 L
20 drops of water ~ 1mL
cubic
centimeter
cm3
1 cm3 = 1 mL
1000 cm3 = 1 L
cube of sugar ~ 1 cm3
microliter
mL
1,000,000 mL = 1 L
crystal of table salt ~ 1 mL
How many milliliters in one liter of water?
How many liters is in a 500mL bottle of
water?
A.
B.
C.
D.
5 liters
2 liters
half a liter (0.5 L)
one liter
Commonly used prefixes in the Metric
system

Example: Convert 20.3 milliliters to Liters
The reference standard kilogram, housed in
Sevres, France


The standard for the SI unit of mass is a machined cylinder
made from an alloy of 90% platinum and 10% iridium (by
weight).
The kilogram is the only SI unit that is still defined based on
a physical artifact rather than on a reproducible property.
Common Metric units of Mass
Unit
Symbol
relationship
example
Kilogram
(base unit)
kg
1 kg = 1000 g
small textbook ~1 kg
gram
g
1
1g 
kg
1000
paper clip ~ 1g
(nickel ~ 5 g)
milligram
mg
1000 mg = 1 g
10 grains of salt ~ 1mg
microgram
mg
1000000 mg = 1 g
particle of baking powder ~ 1 mg
summary



3.3
The scientific and engineering community uses “SI” units based on
the metric system.
 Length – Meter
 Volume – cubic meter
 Mass – kilogram
 Temperature - Kelvin
 Time - second
Prefixes such as kilo (1000x), centi- (0.01x) and mili- (0.001x) are
frequently used with units.
Weight is the force of gravity…. mass is the amount of matter.
Kilo- Hecta- DecadecicentimilliKing Henry Died (Monday) Drinking Chocolate Milk