Transcript Metric System

Measurements
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The Metric system was developed in France
during the Napoleonic reign of France in the
1790's.
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Which other countries, besides the
U.S., do not use the metric system?
According to a survey taken many years ago, the only other
countries that have not officially adopted the metric
system are Liberia (in western Africa) and Myanmar (also
known as Burma, in Southeast Asia).
Accurate Measurements
•Accurate=how close the measurement is to the actual
measurement.
•Be sure we can compare our measurements to other people.
•Scientists make repeated
measurements to increase the validity
and reliability of the results.
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Precision:
Accuracy vs. precision
When taking the
same
measurement
over and over
you get the same
results.
Accuracy:
How close your
results are to the
TRUE/REAL
results
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• A Measurement system
1. must be agreed upon and
2. cannot change
Ex: The foot.
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Le Systeme Internationale d’Unites (SI)
•1960
•Based on Metric System
Standards
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• Exact quantity that people agree to use for a certain
measurement.
• Ex: The meter
• The speed that light travels in a vacuum 1/299 792 458
of a second.
• Why….This seems CRAZY!!!
• The meter Clip
Another Example of a Standard
…..The kilogram
The official
kilogram, made of
platinum-iridium,
remains in France
at the
International
Bureau of Weights
and Measures
Clip
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Le Systeme Internationale
d’Unites (SI)
•English: International
System of Units
•Each measurement
has a base unit.
SI System
•
•
•
•
Based on multiples of ten.
Examples of base units
Length
•Temperature
– Meter
-Kelvin
Mass
•Energy
– Gram
-Joule
•Electric Current
Volume
-Ampere
– Liter
Time
– Second
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Prefixes
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• Prefixes are used with the base units to indicate
what multiple of ten should be used.
• The most common prefixes are:
PrefixSymbol
Multiple
 Kilok
1,000
Hectoh
100
DecaD
10
Decid
.1
Centic
.01
Milim
.001
BASE
UNIT
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Distance
Meter Stick
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•1m = 100 Centimeters
•1m = 1000 millimeters
Each line on the meter stick is a millimeter.
1cm = 10 mm
Meter Stick
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The last digit in all measurements
is an estimate digit.
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Amount of matter in an object
300 +70 +3.31
=373.31g
Triple Beam Balance
Grams
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Space occupied
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Length x Height x Width =Volume
Graduated Cylinder
Volume
•Space an object occupies
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Metric Conversions
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• A conversion is changing the
way you state the same
amount!
• Ex: 1 dollar
– 4 quarters, 100 pennies, 10 dimes
• 1meter = 100centimeters
• Simply move your decimal
point.
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Let’s do some practice
problems
YEAH!
2612
Kinetic Energy
2717
Temperature
Fahrenheit vs. Celsius vs. Kelvin
1714:Daniel Gabriel
Fahrenheit (16861736)
Lord Kelvin
(1824-1907)
Video Clip
1742, Anders
Celsius (1701-1744)
Superfridge
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Mass per unit Volume
Derived Units
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Obtained by combining different units.
Ex: Density
Density is the amount of mass per unit volume.
D = m/v
TYPES OF DATA
Quantitative vs. Qualitative
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• If the data collected involve observations without
measurements or numbers, then it is referred to as
qualitative data.
• Quantitative data involves numbers or
measurements.
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• Extras…
Significant Figures
For measured numbers,
significant figures relate the
certainty of the measurement.
As the number of significant
figures increases, the more
certain the measurement.
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Your answer cannot be more
accurate than the equipment
used to make the measurement.
The accuracy of the result is
limited by the least accurate
measurement.
Sig Fig Rules