SI Units and Prefixes Unit Conversions Scientific Notation Physical Science SI Units and Prefixes Unit Conversions Scientific Notation

SI Units and Prefixes SI units are standardized units of measurement used throughout the world. were developed in France in 1790. share some common units with the older metric system…often referred to as the metric system.

Is the USA a metric country? The USA is and always has been a metric country. For instance, the military in the revolutionary war obtained equipment and training from France…France was metric, so the US military became metric. We are the only country to have our currency based on the metric idea (10 pennies = 1 dime; 10 dimes = 1 dollar) Most items manufactured or imported into the US are measured using metric units.

SI Units Quantity Unit Abbreviation Length Meter m Volume Cubic meter Mass Kilogram kg Time Second s Temperature Kelvin K Electric current Ampere A Amount of Substance Mole Mol or n Luminous Intensity Candela cd

Non-SI Units and Derived Units Quantity Unit Abbreviation Volume liter L Temperature Degree Celsius oC Energy Joule J Force Newton N

SI Prefixes Prefix Symbol Meaning Multiple of base unit giga- G billion 1000000000 mega- M million 1000000 kilo- k thousand 1000 deci- d tenth 0.1 centi- c hundreth 0.01 milli- m thousandth 0.001 micro- millionth 0.000001 nano- n billionth 0.000000001

Unit Conversion Often it is necessary to convert between one unit (such as 32.0mm) to another unit (such as m) when working with data. When converting between units, the mathematical technique of unit analysis may be used:

Unit Conversion To perform a unit analysis, you need to: know the relationship(s) between the units. Look at the equalities from the prefixes, chemical equation, etc. set the equalities into fraction form so that the units cancel until you are left with the desired unit.

Unit Conversion Example Little Johnny measures the mass of a sample to be 562.85cg. He needs to convert this to kilograms. How would you go about solving this problem? Equalities between units: 1cg = 0.01g 1000g = 1kg Set equalities as fractions and cancel

Unit Conversion Practice Set Perform the following: Give the equality between centigrams and decigrams. Give the equalities between kilometers and millimeters. Convert 56.8dg to cg. Convert 0.002km to mm.