And, one other piece of terminology is that if the density is constant,

in other words, the density of the fluid doesn't change as we change the pressure,

then we call that fluid an incompressible fluid, or constant density.

And, generally for

this course, we will assume that all of the fluids are incompressible.

In other words the density is constant and this will even apply to air.

Particular values that we'll be encountering very often is the density

of water rho W, is approximately 1,000 kilograms per cubic meter,

or 62.4 pounds mass per cubic foot.

The specific weight of water under standard conditions

is either 9,810 newtons per cubic meter or

62.4 pounds force per cubic foot.

Now let's do some examples and the first one is that

we're given that gasoline has a density of 680 kilograms per cubic meter.

The specific weight is most nearly which of these alternatives?