Question

water flows through a converging-diverging duct. at the throat of the duct the velocity attained by water is close to the local sound speed in water. then the flow is incompressible as the fluid is water which is incompressible the flow is compressible the flow is incompressible as for water, the flow should attain more than double the sound speed to be compressible more information is required to assess if the flow is compressible

Answer 1

Pressure at a depth h below the surface of water=atmospheric pressure + pressure due to water column of height h.If atmospheric pressure is P, then 2P=P + hρg or hρg = PBut P=10 N cm–2=l0N/(10–2 m)2=105 N m–2Hence h=P/ρg=105/(103 × 9.8)=10.2 mThus a water column of height 10.2 m exerts a pressure equal to the atmospheric pressure.