This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Velocity of Pressure Pulse in a Fluid and Stagnation Properties”.

1. An incompressible fluid is one for which density does not change with change in ____

a) pressure

b) temperature

c) velocity

d) all of the mentioned

View Answer

Explanation: In an incompressible fluid, either density does not change or changes very little.

2. A compressible fluid is one for which density changes with change in temperature, pressure or velocity.

a) true

b) false

View Answer

Explanation: This is opposite to an incompressible fluid.

3. Liquids are ____ and gases are ____

a) both are compressible

b) both are incompressible

c) incompressible, compressible

d) compressible, incompressible

View Answer

Explanation: Liquids are incompressible whereas gases are compressible.

4. The pressure wave velocity c is given by

a) 1 / (dp/d(density))

b) sqrt(dp/d(density))

c) sqrt(d(density)/dp)

d) (dp/d(density))

View Answer

Explanation: Here dp is the change in pressure.

5. For an ideal gas, velocity of sound is given by

a) 1/ɣ*R*T

b) sqrt(1/ɣ*R*T)

c) sqrt(ɣ/RT)

d) sqrt(ɣ*R*T)

View Answer

Explanation: Here R is the characteristic gas constant.

6. The lower the molecular weight of fluid, ____ the value of ɣ and ____ is the sonic velocity at same temperature.

a) lower, lower

b) higher, higher

c) lower, higher

d) higher. lower

View Answer

Explanation: This comes from the expression of velocity of sound in an ideal gas.

7. The Mach number is given by

a) (c/V)^{2}

b) (V/c)^{2}

c) V/c

d) c/V

View Answer

Explanation: Here V is the actual velocity and c is the sonic velocity.

8. For the isentropic stagnation state,

a) it is a reference state

b) designated with subscript zero

c) both of the mentioned

d) none of the mentioned

View Answer

Explanation: It is a reference state in compressible fluid flow.

9. The reference temperature To and normal temperature T are related by

a) (To/T) = 1 + (V^{2})/(2*cp*T)

b) (To/T) = 1 – (V^{2})/(2*cp*T)

c) (To/T) = 1 + (V^{2})/(cp*T)

d) (To/T) = 1 – (V^{2})/(cp*T)

View Answer

Explanation: Here cp is the specific heat at constant pressure and V is the actual velocity.

10. The reference temperature To and normal temperature T can be related in terms of M by

a) (To/T) = 1 + (ɣ-1)*(M^{2})

b) (To/T) = 1 + (ɣ-1)*(M^{2})/2

c) (To/T) = 1 – (ɣ-1)*(M^{2})/2

d) (To/T) = 1 – (ɣ-1)*(M^{2})

View Answer

Explanation: Here M is the Mach number.

**Sanfoundry Global Education & Learning Series – Thermodynamics.**

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