# Fluid Mechanics Test Questions - Set 3

1)   Shear stress in a turbulent flow is given by the formula

τ = η (du / dy)

Where η (eta) is,

a. eddy viscosity
b. apparent viscosity
c. virtual viscosity
d. all of the above
 Answer  Explanation  Related Ques ANSWER: all of the above Explanation: No explanation is available for this question!

2)   Magnitude of eddy viscosity for laminar flow is

a. less than zero
b. zero
c. greater than zero
d. unpredictable
 Answer  Explanation  Related Ques ANSWER: zero Explanation: No explanation is available for this question!

3)   Kinematic eddy viscosity (ε) is the ratio of

a. eddy viscosity (η) to dynamic viscosity (μ)
b. eddy viscosity (η) to kinematic viscosity (ν)
c. kinematic viscosity to eddy viscosity (η)
d. eddy viscosity (η) to mass density (ρ)
 Answer  Explanation  Related Ques ANSWER: eddy viscosity (η) to mass density (ρ) Explanation: No explanation is available for this question!

4)   Friction factor for laminar flow is given by

a. (Re /64)
b. (64 / Re)
c. (Re / 16)
d. (16 / Re)
 Answer  Explanation  Related Ques ANSWER: (64 / Re) Explanation: No explanation is available for this question!

5)   What is temporal mean velocity?

a. The average of velocities at a point over a certain period of time
b. The average of velocities of a single particle over different locations in a fluid flow
c. None of the above

 Answer  Explanation  Related Ques ANSWER: The average of velocities at a point over a certain period of time Explanation: No explanation is available for this question!

6)   The friction factor in fluid flowing through pipe depends upon

a. Reynold's number
b. relative roughness of pipe surface
c. both a. and b.
d. none of the above
 Answer  Explanation  Related Ques ANSWER: both a. and b. Explanation: No explanation is available for this question!

7)   What is the effect of change in Reynold's number on friction factor in turbulent flow?

a. As the Reynold's number increases the friction factor increases in turbulent flow
b. As the Reynold's number increases the friction factor decreases in turbulent flow
c. change in Reynold's number does not affect the friction factor in turbulent flow
d. unpredictable
 Answer  Explanation  Related Ques ANSWER: As the Reynold's number increases the friction factor decreases in turbulent flow Explanation: No explanation is available for this question!

8)   What is the formula for determining the size of equivalent pipe for two pipes of lengths L1, L2 and diameters d1, d2 respectively?

Where,
L = L1 + L2

a. (L / d) = (L1 / d1) + (L2 / d2)
b. (L / d2 ) = (L1 / d12) + (L2 / d22)
c. (L / d3) = (L1 / d13 ) + (L2 / d23)
d. (L / d5) = (L1 / d15 ) + (L2 / d25)
 Answer  Explanation  Related Ques ANSWER: (L / d5) = (L1 / d15 ) + (L2 / d25) Explanation: No explanation is available for this question!

9)   What is a syphon?

a. A long bend pipe used to carry water from a reservoir at a higher level to another reservoir at a lower level when two reservoirs are separated by a hill
b. A long bend pipe used to carry water from a reservoir at a lower level to another reservoir at a higher level with some work input when two reservoirs are separated by a hill
c. A long bend pipe used to carry water from one reservoir to another reservoir when two reservoirs are at same elevation
d. Unpredictable
 Answer  Explanation  Related Ques ANSWER: A long bend pipe used to carry water from a reservoir at a higher level to another reservoir at a lower level when two reservoirs are separated by a hill Explanation: No explanation is available for this question!

10)   The highest point of syphon is called as

a. syphon top
b. summit
c. reservoir
d. none of the above
 Answer  Explanation  Related Ques ANSWER: summit Explanation: No explanation is available for this question!

11)   Match the following physical quantities in Group 1 with their dimensions in Group 2.

1. Work done (Energy) (W) ----------------------------- A. [M L 2 T – 3 ]
2. Power (P) ------------------------------------------------ B. [M L – 1 T   – 1 ]
3. Momentum (M) ---------------------------------------- C. [M L 2 T – 2 ]
4. Modulus of elasticity (E) ----------------------------- D. [M L T – 1 ]
5. Dynamic viscosity (μ) --------------------------------- E. [M L – 1 T – 2 ]

a. 1-(C), 2-(A), 3-(D), 4-(E), 5-(B)
b. 1-(A), 2-(C), 3-(D), 4-(E), 5-(B)
c. 1-(C), 2-(A), 3-(E), 4-(B), 5-(D)
d. 1-(D), 2-(E), 3-(B), 4-(A), 5-(C)
 Answer  Explanation  Related Ques ANSWER: 1-(C), 2-(A), 3-(D), 4-(E), 5-(B) Explanation: No explanation is available for this question!

12)   Which of the following equations is not dimensionally homogeneous?
Consider standard symbols for quantities.

a. (Force) F = m x a
b. (Head Loss due to friction) hf = (f L V2) / (2 g d)
c. (Torque) T = F x Distance
d. None of the above
 Answer  Explanation  Related Ques ANSWER: None of the above Explanation: No explanation is available for this question!

13)   Which of the following is a dimensionless equation?

a. Reynold's equation
b. Euler's equation
c. Weber's equation
d. All of the above
 Answer  Explanation  Related Ques ANSWER: All of the above Explanation: No explanation is available for this question!

14)   Which of the following number is applicable in open hydraulic structure such as spillways, where gravitational force is predominant?

a. Reynold's Number
b. Euler's Number
c. Weber's Number
d. Froude's Number
 Answer  Explanation  Related Ques ANSWER: Froude's Number Explanation: No explanation is available for this question!

15)   Square root of the ratio of inertia force to elastic force is called as

a. Mach's Number
b. Cauchy's Number
c. Both a. and b.
d. None of the above
 Answer  Explanation  Related Ques ANSWER: Both a. and b. Explanation: No explanation is available for this question!

16)   Boundary layer thickness is the distance from the boundary to the point where velocity of the fluid is

a. equal to 10% of free stream velocity
b. equal to 50% of free stream velocity
c. equal to 90% of free stream velocity
d. equal to 99% of free stream velocity
 Answer  Explanation  Related Ques ANSWER: equal to 99% of free stream velocity Explanation: No explanation is available for this question!

17)   The component of the total force exerted by fluid on a body in the direction parallel to the direction of motion is called as

a. lift
b. drag
c. both a. and b.
d. none of the above
 Answer  Explanation  Related Ques ANSWER: drag Explanation: No explanation is available for this question!

18)   The sum of components of shear forces in the direction of flow of fluid is called as

a. shear drag
b. friction drag
c. skin drag
d. all of the above
 Answer  Explanation  Related Ques ANSWER: all of the above Explanation: No explanation is available for this question!

19)   The body whose surface does not coincide with the streamline when places in a flow is called as

a. streamline body
b. wave body
c. bluff body
d. induced body
 Answer  Explanation  Related Ques ANSWER: bluff body Explanation: No explanation is available for this question!

20)   Which type of body is an airfoil?

a. streamline body
b. wave body
c. bluff body
d. induced body
 Answer  Explanation  Related Ques ANSWER: streamline body Explanation: No explanation is available for this question!

21)   Bulk modulus is the ratio of

a. shear stress to volumetric strain
b. volumetric strain to shear stress
c. compressive stress to volumetric strain
d. volumetric strain to compressive stress
 Answer  Explanation  Related Ques ANSWER: compressive stress to volumetric strain Explanation: No explanation is available for this question!

22)   When is a liquid said to be not in a boiling or vaporized state?

a. If the pressure on liquid is equal to its vapour pressure
b. If the pressure on liquid is less than its vapour pressure
c. If the pressure on liquid is more than its vapour pressure
d. Unpredictable
 Answer  Explanation  Related Ques ANSWER: If the pressure on liquid is more than its vapour pressure Explanation: No explanation is available for this question!

23)   One litre of a certain fluid weighs 8N. What is its specific volume?

a. 2.03 x 10– 3 m3/kg
b. 20.3 x 10– 3 m3/kg
c. 12.3 x 10– 3 m3/kg
d. 1.23 x 10– 3 m3/kg
 Answer  Explanation  Related Ques ANSWER: 1.23 x 10– 3 m3/kg Explanation: No explanation is available for this question!

24)   What is the correct formula for absolute pressure?

a. Pabs = Patm – Pgauge
b. Pabs = Pvacuum – Patm
c. Pabs = Pvacuum + Patm
d. Pabs = Patm+ Pgauge
 Answer  Explanation  Related Ques ANSWER: Pabs = Patm+ Pgauge Explanation: No explanation is available for this question!

25)   According to Archimede's principle, if a body is immersed partially or fully in a fluid then the buoyancy force is _______ the weight of fluid displaced by the body.

a. equal to
b. less than
c. more than
d. unpredictable
 Answer  Explanation  Related Ques ANSWER: equal to Explanation: No explanation is available for this question!