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SI Units are...
InternationInternational al
StandardsStandards
Abbreviated SI from the French Le Abbreviated SI from the French Le Systeme Internationale d’UnitesSysteme Internationale d’Unites
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What is a standard?It is an exact quantity that people agree to use for comparison.Why are measurement
standards important?
A meter in the U.S. is the same as a meter in France, or China, or any other country in the world. This allows us to share data.
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Prefix Symbol Factor Number Factor Word
Kilo K 1,000 Thousand
Hecto H 100 Hundred
Deka DA 10 Ten
deci d 0.1 Tenth
centi c 0.01 Hundredth
milli m 0.001 Thousandth
Prefixes
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centi- meter
milli-liter
kilo-gram
(0.01)
(.001)
(1000)
Putting It All Together…
hundredth of a meter
thousandth of a liter
thousand grams
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SI Units for Measurement Used in Science
Length
Volume
Mass
Temperature
Measured in meters (m)Measured in meters (m)
Measured in Liters (L)Measured in Liters (L)
Measured in grams (g)Measured in grams (g)
Measured in degrees Celsius (Measured in degrees Celsius (OOC)C)
Metric ruler
Graduated cylinder
Balance
Thermometer
Type Base Unit Tool
Time Measured in seconds (s)Measured in seconds (s) Clock
L x W x H
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When measuring an object with a ruler,
never start with at the “0” mark. Rulers are less accurate due to wear and tearwear and tear at the ends. Begin at the 2, 4, 5 or 6 cm mark
in order to get the most accurate mark.
Using a Ruler
The red line would be 1.2 cm1.2 cm because the “5” is the starting point.
What is the length of the red line? 6.2 cm or 1.2 cm
5 6
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Reading the Meniscus
When measuring liquid volume in a graduated cylinder, a meniscus often forms where the liquid ends.
graduated cylinders
In order to read this liquid volume, you must be at “eye-level” to the level of the liquid.You take the reading at the BOTTOMBOTTOM
of the meniscus.The liquid level is 36.5 mL.