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metric prefixes
metric prefixes
At this point in your education, hopefully you've been introduced to metric prefixes. If you were in my physics class last year, you couldn't get away from 'em! Hopefully most of this page is review, but it's still crucial that you've mastered these before moving forward.
The most commonly used metric prefixes in this course are:
◦Mega (M) = 106
◦kilo (k) = 103
◦centi (c) = 10-2
◦milli (m) = 10-3
◦micro (µ) = 10-6
◦nano (n) = 10-9
Fun fact: You can literally just replace the metric prefix with "x 10^[power]" to convert back to base units.
For example: 7.2 nm = 7.2 x 10^(-9) meters.
Be aware that you need to know how to convert from any metric prefix TO any metric prefix.
In the fall semester, everything we encounter can be expressed as a combination of only three base units:
Time --> (Seconds)
Displacement --> (Meters)
Mass --> (Kilograms)
Notice that the base unit of mass is the only one that involves a prefix. This is weird and likely to be a source of mistakes - a "gram" is not the base unit, so when you perform calculations involving mass, it's typically best to convert to kilograms first.
unit conversions
unit conversions
Fractions - you know 'em and love 'em! Recall that when multiplying fractions, you multiply across each numerator and across each denominator. A variable that appears in both a numerator and a denominator is divided out and disappears.
When converting units, treat every unit as a fraction with a variable in the numerator and denominator.
Simple units can be treated as if they have a denominator of "1." (For example - a kilogram is kilogram/1).
When converting units, look at your current numerator and denominator units.
Look at the final numerator and denominator units you need.
Set up conversion factors to cancel units you don’t want and introduce the final units you DO want. See this video for an example:
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