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Physical Science Units Notes.notebook
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January 28, 2016
Measurement
Scientists use a set of measuring units called SI.
Stands for International System of Units
Built upon the metric system
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Base UnitsLength:
Mass:
Temp:
Time:
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Derived Units
Area:
Volume:
Density:
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Metric Conversions
Convert the following:
1000m to Km:
25mg to g:
5Km to cm:
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Conversion FactorsThere is an easy way to convert units both in and out of the metric system.
All you need is a conversion factor. Conversion factors are like reversible fractions that you can use to go back and forth between units.
Examples: Write the conversion factors
(1 mile=5280ft)
(1Kg=1000g)
(1000mL = 1L)
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Using Conversion FactorsConversion factors are used by multiplying and canceling units.
Example:
Convert 2.5 miles to feet
Convert 4882 feet to miles
Convert 389 Kg to grams
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Converting Celsius to KelvinIf your temperature is in Celsius, simply add 273 to get to Kelvin.
Convert 34O C to Kelvin
Convert 299 Kelvin to Celsius
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Precision vs. Accuracy
Precision: How close your results are to a given value.
Accuracy: How close your results are to the CORRECT value
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Percent ErrorWe can use a mathematical solution to find out exactly how inaccurate we were.
The formula for percent error is:
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Solving for Percent Error
The known value for the density of gold is 19.3 g/cm3. After doing an experiment you found the density of gold to be 19.8 g/cm3. What is your percent error?
Were your results accurate?
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The known density for copper is 8.96 g/mL. You found that the density of copper was 2.3 g/mL. What was your percent error?
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Solving for DensityThe "magic triangle"
Remember your units:
Mass
Volume
Density
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A material has a volume of 35mL and a mass of 52g. What is the density of the material?
A material has a mass of 25g and a density of 99 g/mL. What is the volume of the object?
A material has a density of 3.3 g/cm3 and a volume of 2.6 mL. What is the mass of the object?
Solving For Density
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