I want to complete this discussion of fluid properties with a few comments on

properties and units that we'll be using.

These are some tables which are extracted from the FE manual, and,

for example, the left hand table gives some properties of water in metric units,

temperature, specific weight in kilonewtons per cubic meter,

density in kilograms per cubic meter dynamic viscosity.

And here they use a, a new, you'll notice a new unit.

It's shown as Pa S.

This stands for Pascal seconds.

And all you need to know here is that a Pascal second is just the same as a Newton

second per square meter, or kilograms per meter second.

Then we have tables of kinematic viscosity in units of meter squared per second, and

finally vapor pressure, but vapor pressure we won't you, be using in this course.

The right hand table are properties of water in English units.

And here, the temperature is given in degrees Fahrenheit,

specific weight pounds force per cubic foot, and then density row.

But here, unfortunately they've given the density of different units.

In pound four second squared per foot to the fourth, and

the number there they give typically is 1.94.

In those units throughout the examples here,

the density will be given in units of pounds mass per cubic foot.

And the density in pounds mass per cubic foot is approximately 62.4.

These units here, where they give it here,

are actually slugs per cubic foot, which is another unit of mass.

So, unfortunately the the manual is not consistent in the way they use the units,

so we need to be careful about that.

The dynamic viscosity in pound-force second per square foot, that's all right,

that's consistent.

And similarly the kinematic viscosity

in units of feet squared per second is also consistent.

But sometimes you do have to be careful in the manual in the examples

because they're not consistent in their uses of units.

In different places in the manual, they give the properties.

Also, here are properties of gasses.

For example, air here, which we'll be most usually concerned with.

And here properties of selected liquids and gasses.

For example, water.

And here you see the density of water is given differently.

There it is given in british units

in terms of pounds mass per square by cubic foot.

And the number there is 62.4 is the more common one.