STATEMENT-1: The stream of water flowing at high speed from a garden hose pipe tends to spread like a fountain when held vertically up, but tends to narrow down when held vertically down.
STATEMENT-2: In any steady flow of an incompressible fluid, the volume flow rate of the fluid remains constant. [2008]
(1)
The volume flow rate (Q) of an incompressible fluid in steady flow remains constant.
From equation of continuity, = constant
where = area of cross-section and = velocity
If decreases, increases and vice-versa.
When stream of water moves up, its speed decreases and therefore increases i.e. the water spreads out as a fountain. When stream of water from hose pipe moves down, its speed increases and therefore area of cross-section decreases.