Watching this resources will notify you when proposed changes or new versions are created so you can keep track of improvements that have been made.
Favoriting this resource allows you to save it in the “My Resources” tab of your account. There, you can easily access this resource later when you’re ready to customize it or assign it to your students.
Now that we know about the SI system and what it provides to the scientist and engineer, we can examine some aspects of actual measurement. The SI system utilizes a standard system of prefixes to the basic units that allow them to be more relevant to and descriptive of relative magnitude.
For example, when reading about chemical kinetics, you may encounter the terms "ms" or "ns," meaning "millisecond" and "nanosecond" respectively. Once you've become accustomed to the practice of using the prefixes, you will immediately know that the millisecond is 1/1000 of one second and is 1 million times larger than a nanosecond, which is 1/1000000000 of one second, or 10-9 seconds.
Briefly review the basic SI units before you study the prefixes.
The basic SI units
The basic units of the SI system.
There are 20 accepted prefixes. A prefix may be used to identify multiples of the original unit or fractions of the original unit. For example, kilo- denotes a multiple of a thousand, so there are one thousand meters in a kilometer. Milli- denotes a thousandth; therefore, there are one thousand millimeters in a meter.
Prefixes for SI units
The prefixes redefine the measurement as either a multiple or a fraction of the basic unit.
Keep in mind that prefixes should never be combined. Thus a millionth of a meter is a micrometer, not a millimillimeter, and a millionth of a kilogram is a milligram, not a microkilogram.
In older usage, a micron (a measurement often encountered in physics and engineering) is the same as a micrometer, 10-6 meters. Another older form of usage, the millimicron, is one thousandth of a micrometer, or 1 thousandth of 10-6 meters, or 10-9 meter, now called a nanometer. While these older terms are not in common usage, they are often encountered in older publications, and knowing their modern equivalents is an advantage.
Assign this as a reading to your class
Assign just this concept, or entire chapters to your class for free. You will be able to see and track your students' reading progress.