Thermodynamics Multiple Choice Questions on “Normal Shocks”.
1. Shock waves are highly localized irreversiblities in flow.
a) true
b) false
Answer: a
Clarification: This is a basic fact about shock waves.
2. Normal shocks can be treated as shock waves parallel to the flow.
a) true
b) false
Answer: b
Clarification: Normal shocks can be treated as shock waves perpendicular to the flow.
3.Within the mean free path of molecule, flow passes from
a) supersonic state
b) subsonic state
c) subsonic to supersonic state
d) supersonic to subsonic state
Answer: d
Clarification: This happens within distance of mean free path of molecule.
4. When flow passes from supersonic to subsonic state,
a) pressure increases
b) velocity decreases
c) both of the mentioned
d) all of the mentioned
Answer: c
Clarification: As velocity decreases, pressure increases.
5. The impulse function is given by
a) F = p*A + (density)*A*(V2)
b) F = p*A + (density)*A*V
c) F = p*A + (density)*A*sqrt(V)
d) none of the mentioned
Answer: a
Clarification: This is the impulse function.
6. Fanno line represents the locus of points with same mass velocity and stagnation enthalpy.
a) true
b) false
Answer: a
Clarification: The Fanno line can be represented on h-v coordinate or h-(1/density) coordinate.
7. The end states of normal shock must ____ Fanno line.
a) lie below
b) lie above
c) lie on
d) none of the mentioned
Answer: c
Clarification: They must lie on the Fanno line.
8. Which of the following is true about adiabatic flow in constant area duct with friction?
a) it has constant G
b) it has constant ho
c) it follows Fanno line
d) all of the mentioned
Answer: d
Clarification: This is true for adiabatic flow in one directional model.
9. The impulse pressure(I) is given by
a) F/A
b) p + (density)(V2)
c) p + (G2)/(density)
d) all of the mentioned
Answer: d
Clarification: These all are the relations of impulse pressure.
10. Rayleigh line represents the locus of states with same impulse pressure and mass velocity.
a) true
b) false
Answer: a
Clarification: The end states of normal shock must lie on Rayleigh line also.