Take another look at Figure 4.3.3 in the previous section. Notice how it talks about the “SI unit” used to describe work? You can also see that there is a little section describing “Other units”. Wikipedia is following the scientific and international standard of using the SI System. So what is the SI system and why did Canada risk crashing an airplane to switch?
SI stands for The International System of Units. It is derived from the french, French Le Système International d’Unités (hence the seemingly back words abbreviation, SI). The SI system is commonly referred to as the metric system and both metric and SI will be used interchangeably throughout the book. The history of SI is pretty interesting. Watch the following video to get a feel for how SI units came to be.
Let’s say that you get elected President of the United States and you make the decision that the US should switch to SI. You make an executive order, and overnight, the US is supposed to switch to the metric system. For this discussion, think of one good consequence, and one potentially disastrous consequence from America switching to metric overnight.
If you are stumped, think about areas where this unit change would be helpful? How might the shift to metric overnight change people’s work life? What about their home life?
There are three main concepts that you need to fully understand the SI system: The Base Units, Derived Units, and Metric Prefixes. Once you understand these three concepts you are well on your way to being an SI expert! Do you notice the similarities of “The Base Units” and “Derived Units” to our sections on dimensions?
