Q.

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 Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1  
2 Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1  
3 Statement-1 is True, Statement-2 is False  
4 Statement-1 is False, Statement-2 is True  

Ans.

(1)

The volume flow rate (Q) of an incompressible fluid in steady flow remains constant.

From equation of continuity, av = constant

 Q=a×v=constant or,  a1v

where a = area of cross-section and v = velocity

If v decreases, a increases and vice-versa.

When stream of water moves up, its speed (v) decreases and therefore 'a' 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.