1. SI Units and Prefixes Unit Conversions Scientific Notation
Physical Science
SI Units and Prefixes
Unit Conversions
Scientific Notation

2. SI Units and Prefixes SI units
are standardized units of measurement used throughout the world.
were developed in France in 1790.
share some common units with the older metric system…often referred to as the metric system.

3. Is the USA a metric country?
The USA is and always has been a metric country. For instance,
the military in the revolutionary war obtained equipment and training from France…France was metric, so the US military became metric.
We are the only country to have our currency based on the metric idea (10 pennies = 1 dime; 10 dimes = 1 dollar)
Most items manufactured or imported into the US are measured using metric units.

4. SI Units Quantity Unit Abbreviation Length Meter m Volume Cubic meter
Mass
Kilogram kg
Time
Second s
Temperature
Kelvin K
Electric current
Ampere A
Amount of Substance
Mole
Mol or n
Luminous Intensity
Candela cd

5. Non-SI Units and Derived Units
Quantity
Unit
Abbreviation
Volume
liter L
Temperature
Degree Celsius oC
Energy
Joule J
Force
Newton N

6. SI Prefixes Prefix Symbol Meaning Multiple of base unit giga- G
billion
mega- M
million
kilo- k
thousand
1000
deci- d
tenth
0.1
centi- c
hundreth
0.01
milli- m
thousandth
0.001
micro-
millionth
nano- n
billionth

7. Unit Conversion
Often it is necessary to convert between one unit (such as 32.0mm) to another unit (such as m) when working with data. When converting between units, the mathematical technique of unit analysis may be used:

8. Unit Conversion To perform a unit analysis, you need to:
know the relationship(s) between the units. Look at the equalities from the prefixes, chemical equation, etc.
set the equalities into fraction form so that the units cancel until you are left with the desired unit.

9. Unit Conversion Example
Little Johnny measures the mass of a sample to be cg. He needs to convert this to kilograms. How would you go about solving this problem?
Equalities between units:
1cg = 0.01g g = 1kg
Set equalities as fractions and cancel

10. Unit Conversion Practice Set
Perform the following:
Give the equality between centigrams and decigrams.
Give the equalities between kilometers and millimeters.
Convert 56.8dg to cg.
Convert 0.002km to mm.