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Unit Conversions Factor Label Method. Dimensional Analysis Factor Label Method. Measurements that are made of some aspect of the universe must have a quantity and a unit Many times, values are not measured in the unit that we want
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Dimensional AnalysisFactor Label Method • Measurements that are made of some aspect of the universe must have a quantity and a unit • Many times, values are not measured in the unit that we want • We have to do some math to get the numbers in the form that we desire
Dimensional AnalysisFactor Label Method • To convert a measurement from one unit to another, multiply the known quantity and unit(s) by a conversion factor
Conversion Factors • The chosen conversion factor cancels all units except those desired for the answer • Conversion Factors come from equalities • Equalities yield two conversion factors: • 1 ft = 12 in
Conversion FactorsChoosing the Correct Conversion Factor • Example: Convert 179,800 s to minutes
Conversion FactorsChoosing the Correct Conversion Factor • Write Measurement with wrong units • Write “Multiplication Sign, Fraction Bar” • Write the unit that you want to cancel on the bottom of the fraction. Write the desired unit on the top of the fraction • Fill in the fraction with the numbers that make the numerator & denominator of the fraction equivalent • Cancel Units → PLUG & CHUG!!! → Round to the proper number of SF
Conversion FactorsMultiple Steps • Each conversion factor should cancel out a unit from the previous measurement (or conversion factor) • Convert 179800 s to days
Conversion FactorsMultiple Steps with Complex Units • Each conversion factor should cancel out a unit from the previous measurement (or conversion factor) • Convert 65.0 mi/hr to m/s • 1 mi = 1.6 km