052:041 Process Calculations Topic 2 Lesson 2 p. 3

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Topic 2 Lesson 2
Units and dimensions, systems of units, dimensional homogeneity

AES, CGS, SI, Unit Prefixes

American Engineering System of Units

This system is based largely upon the English system of units that was adopted when the Magna Carta was signed in 1215 A.D.

CGS System of Units

The centimeter, gram, second system was devised in 1790 by the National Assembly of France in an attempt to establish a broadly accepted system of units.

SI System of Units

	American Engineering System	CGS System	SI System
Length	foot	centimeter	meter
Mass	lb_m	gram	kilogram
Amount	lb-mole	mole	mole
Time	second	second	second
Temperature	Fahrenheit	Kelvin	Kelvin
Volume	gallon	cm³	meter³
Force	lb_f	dyne	Newton
Pressure	psi	dyne/cm²	Pascal
Energy	btu	calorie or erg	Joule

New York to Chicago

When choosing a multiple unit, pick the one that allows you to express the measured value as a number between 0.1 and 1000.

For example:

Distance from New York to Chicago = 52,018,560 inches vs 821 miles

Driving time for this trip = 53,580 seconds vs 14.9 hours

Multiple unit prefixes

Prefix	Symbol	Factor
tera	T	10¹²
giga	G	10⁹
mega	M	10⁶
kilo	k	10³
deci	d	10^-1
centi	c	10^-2
milli	m	10^-3
micro	µ	10^-6
nano	n	10^-9
pico	p	10^-12
femto	f	10^-15

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Topic 2 Lesson 2 Units and dimensions, systems of units, dimensional homogeneity

AES, CGS, SI, Unit Prefixes

American Engineering System of Units

CGS System of Units

CGS System of Units

SI System of Units

SI System of Units

New York to Chicago

New York to Chicago

Multiple unit prefixes

Multiple unit prefixes

Page 3 of 15

Topic 2 Lesson 2
Units and dimensions, systems of units, dimensional homogeneity