Have you ever used your thumb to control the water flowing from the end of a hose?
If so, you probably have seen that the water's velocity increases when your thumb
reduces the cross-sectional area of the hose opening.
This kind of fluid behavior is described by the equation of continuity , which
expresses the simple idea that the mass of fluid entering one end of a pipe must
leave at the other end. In other words, the mass flow rate (in kilograms per second)
must be the same when entering and leaving a pipe.
= change in time (seconds)
= density of fluid ()
= cross-sectional area of pipe ()
= velocity of fluid (m/s)
Whereas the mass flow rate when the fluid comes out of a pipe (or position 2)
is written as :