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Steady, compressible flow of air takes place through an adiabatic converging-diverging nozzle, as shown in the figure. For a particular value of pressure difference across the nozzle, a stationary normal shock wave forms in the diverging section of the nozzle. If E and F denote the flow conditions just upstream and downstream of the normal shock, respectively, which of the following statement(s) is/are TRUE?

1. Static pressure at E is lower than the static pressure at F
2. Density at E is lower than the density at F
3. Mach number at E is lower than the Mach number at F
4. Specific entropy at E is lower than the specific entropy at F

Correct answer: Specific entropy at E is lower than the specific entropy at F

Solution

In a normal shock wave, the flow experiences an increase in entropy due to irreversible processes, which means that the specific entropy downstream of the shock (at point F) is higher than upstream (at point E). This aligns with the thermodynamic principles governing shock waves in compressible flow.

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