Section 4.5 The Base Units

The SI base units are the building blocks of the whole system. They are analogous to the fundamental dimensions discussed in this chapter earlier. Since the units are simply descriptors of the quantity of a dimension, let’s go ahead and pair them up!

So when we want to talk about the height of a basketball player, a scientist (or as we learned from the video, anyone not in the US, Myanmar, or Liberia) would say that Nikola Jokic is 2.11 meters tall. The dimension is length and the SI unit for length is the meter. Similarly, in the SI system Michael Jordan is listed as having a mass of 98 kg. The dimension, in this case, is mass, and the associated SI unit is the kilogram.

The only common exception to this rule is for the dimension of time. If you ask a scientist how old Nikola Jokic is it is highly unlikely that they would reply that he is 1767226000 seconds old unless they were really into the SI system. However, for any of the other dimensions listed above, you should use the SI unit for the dimension when you can.