What are Units and Why Are They Important?

We use conversion factors to convert one unit to another unit for the same dimension.

For example, let's convert a density of
1 g/cm3 to units of lbm/ft3.

A numerical result without units is not acceptable unless
the result is dimensionless.

Units can also guide you to the solution of a problem or help you determine if your solution is correct.

If the units are not correct, then your solution probably has an error.


Let's consider the water in a beaker again:

grams (g) or pounds mass (lbm)

Common units for mass:

Common units for density:

grams per cubic centimeter (g/cm3)
or pounds mass per cubic foot (lbm/ft3)
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Ch 1, Lesson B, Page 2 - What are Units and Why Are They Important?