INSTRUCTOR: In this screen cast,
we're going to compare the two systems of units
that you might be using,
SI units and American units.
And we'll start with the base units.
So for length, the SI unit
is the meter.
However, you will sometimes see
some multiple of the meter in your calculations.
So you might have a kilometer
or a centimeter,
but the SI unit is the meter.
So in American units,
the length that you're going to use is the foot.
However, you will also have calculation
in inches and even miles.
So we have for a meter, we have an "m,"
kilometer, and centimeter.
For American units,
for a foot, "ft,"
and an inch is "in."
So let's go to mass.
So if you're asked for it in SI units,
it's the kilogram,
but you will also do,
especially when you're doing smaller quantities,
you'll work in the gram.
For American units, what we use for mass is the pound,
and these are our abbreviated kilogram
or gram or pound.
With moles, in SI units, we have what's known as the mole
or technically the gram mole,
but you can also have the kilogram mole
for larger quantities.
In American units, we deal with pound moles.
Now, note, when we are writing out moles in our symbols,
we drop that "e."
So it'd be "mols," or it would be kilomole,
or it would be pound moles.
For time, the SI unit is the second.
And all the time units are the same
for both SI and American units.
But you can also see things in minutes, as well as hours,
and occasionally, for long periods of time,
you can see a day or a month or a year.
So, again, as I said, the American units are the same.
And so we abbreviate this "s" for second,
"min" for minute,
and "h" for hour.
And finally, we look at temperature.
So the unit, the base unit for SI is Kelvin,
but you can also see it in Celsius.
When we're looking at American units,
we usually use Fahrenheit.
However, you'll also see it in Rankine.
Note for Kelvin, you just have a "K,"
but it's degrees Celsius, degrees Fahrenheit,
and degrees Rankine.
Now we're gonna look at what are known as derived units,
and here in this chart,
we're only gonna look at the SI units.
So "derived" means that you take some combination
of the base units to make a derived unit.
So in SI units, the unit is the liter,
and I'll write it as "L,"
and in terms of base units,
this is 0.001 meters cubed.
Now we look at force, and we use the newton,
which is our big "N."
And that's equal to a kilogram meter per second squared.
Pressure, we use what's known as the pascal.
Sometimes you'll also see a kilopascal.
We abbreviate that "Pa,"
and that's equal to one newton per meter squared.
Now energy or work.
We work with the joule, and that's abbreviated with a "J."
And that's equal to
a kilogram meter squared per second squared.
And finally, power, which is a watt, capital "W."
A watt is equal to a joule per second,
which ends up being
kilogram meters squared per second squared.