Unit Conversions Factor Label Method

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. We have to do some math to get the numbers in the form that we desire.

Dimensional Analysis Factor Label Method To convert a measurement from one unit to another, multiply the known quantity and unit(s) by a conversion factor Quantity with x Conversion = Quantity with Wrong Unit Factor Desired Unit

Conversion Factors Conversion Factors come from equalities Equalities yield two conversion factors:  1 ft = 12 in OR

Factor Label Method Example Convert 179,800 s to minutes Think of the relationship(s) between the unit you are given and the desired unit. 1 min = 60 sec From this equality, we get two conversion factors: OR

When determining the amount of significant figures for our answer, we only look at measurements given by the problem. We never consider conversion factors when determining the amount of significant figures for our answer!

Kilo- Hecto- Deka- Base Unit Deci- Centi- Milli- grams liters meters 1 kg = 1000 g 1 hg = 100 g 1 dkg = 10 g 1 g = 10 dg 1 g = 100 cg 1 g = 1000 mg Metric Conversions