Law of continuity problem in fluids

[Dingu Sagar]

When a hose with running water is partially blocked with our finger ,the water comes out with a greater velocity. This is in agreement with the law of continuity in fluids which states that velocity of fluid is inversely proportional to the area of cross section.

But when a running tap is closed partially , the water velocity decreases even though the area has been reduced by the tap. Why is the phenomenon not explainable by the above law ?

 

[Delta2]

When a hose with running water is partially blocked with our finger ,the water comes out with a greater velocity. This is in agreement with the law of continuity in fluids which states that velocity of fluid is inversely proportional to the area of cross section.

The law of continuity doesn't state that exactly. What is marked in bold is true only if the flow of fluid is incompressible i.e the fluid density remains constant with respect to time.

But when a running tap is closed partially , the water velocity decreases even though the area has been reduced by the tap. Why is the phenomenon not explainable by the above law ?

That happens because the valve in the tap is designed in such a way as to make the flow compressible .