730+ Fluid Mechanics and Hydraulic Machines Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Civil Engineering , Mechanical Engineering .

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51.	High velocity flow in a conduit of large size is known as
A.	Laminar flow
B.	Turbulent flow
C.	Either of the above
D.	None of the above.
Answer» B. Turbulent flow

discuss

52.	If the Reynolds number is less than 2000, the flow in a pipe is
A.	Laminar flow
B.	Turbulent flow
C.	Transition flow
D.	None of the above.
Answer» A. Laminar flow

discuss

53.	The path followed by fluid particle in motion is called a
A.	Streamline
B.	Path line
C.	Streak line
D.	None of the above.
Answer» B. Path line

discuss

54.	A....is an imaginary line within the flow so that the tangent at any point on it indicates the velocity at that point.
A.	Streak line
B.	Stream line
C.	Path line
D.	None of the above.
Answer» B. Stream line

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55.	A stream line is one
A.	In which stream function does not change
B.	In which the flow cannot cross the bounding surface
C.	Which has a constant area throughout its length so that the velocity remains constant.
D.	None of the above.
Answer» B. In which the flow cannot cross the bounding surface

discuss

56.	...... is a curve which gives an instantaneous picture of the location of the fluid particles which have passed through a given point.
A.	Path line
B.	Stream line
C.	Streak line
D.	None of the above.
Answer» C. Streak line

discuss

57.	In fluid mechanics, the continuity equation is a mathematical statement embodying the principle of
A.	Conservation of momentum
B.	Conservation of mass
C.	Conservation of energy
D.	None of the above.
Answer» B. Conservation of mass

discuss

58.	An irrational flow is one in which
A.	The stream lines of flow are curved and closely spaced
B.	The fluid does not rotate as it moves along
C.	The net rotation of fluid particles about their mass centres remains zero
D.	None of the above.
Answer» C. The net rotation of fluid particles about their mass centres remains zero

discuss

59.	In a fluid-flow the stream lines are lines
A.	Along which the vorticity is zero
B.	Along which the stream function ψ = constant
C.	Which are parallel to the equipotential lines
D.	Which exist in irrotional flow only.
Answer» B. Along which the stream function ψ = constant

discuss

60.	....... is defined mathematically as the line integral of the tangential velocity about a closed path (contour).
A.	Circulation
B.	Vorticity
C.	Either of the above
D.	None of the above.
Answer» A. Circulation

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61.	The concept of stream function which is based on the principle of continuity is applicable to
A.	Irrotational flow only
B.	Two-dimensional flow only
C.	Three-dimensional flow
D.	Uniform flow only.
Answer» B. Two-dimensional flow only

discuss

62.	The motion is described as ......when the components of rotation or vorticity are zero throughout certain point of the fluid.
A.	Rotational
B.	Irrotational
C.	Either of the above
D.	None of the above.
Answer» B. Irrotational

discuss

63.	........ is defined as a scalar function of space and time such that its negative derivative with respect to any direction gives the fluid velocity in that direction.
A.	Velocity potential function
B.	Stream function
C.	Circulation
D.	Vorticity.
Answer» A. Velocity potential function

discuss

64.	If velocity potential (φ) satisfies the Laplace equation, it represents the possible..... flow.
A.	Unsteady, compressible, rotational
B.	Steady, compressible, irrotational
C.	Unsteady, incompressible, rotational
D.	Steady, incompressible, irrotational.
Answer» D. Steady, incompressible, irrotational.

discuss

65.	A flow net is a graphical representation of strea lines and equipotential lines such that these lines
A.	Intersect each other orthogonally forming curvilinear squares
B.	Intersect each other at various different angles forming irregular-shaped nets
C.	Indicate the direction and magnitude of vector
D.	None of the above.
Answer» A. Intersect each other orthogonally forming curvilinear squares

discuss

66.	Velocity head is given by
A.	V/g
B.	V2/2g
C.	V3/2g
D.	V2/2g2
Answer» B. V2/2g

discuss

67.	Euler’s equation (in differential form) is written as:
A.	dp/ρ + v2.dv + g.dz = 0
B.	dp/ρ + v.dv + g.dz = 0
C.	dp/ρ + v.dv + g2.dz = 0
D.	dp/ρ2 + v.dv + g.dz = 0
Answer» B. dp/ρ + v.dv + g.dz = 0

discuss

68.	In which of the following measuring devices Bernoulli’s equation is used:
A.	Venturimeter
B.	Orificemeter
C.	Pitot tube
D.	All the above.
Answer» D. All the above.

discuss

69.	The co-efficient of discharge of an orificemeter is ......that of a venturimeter.
A.	Equal to
B.	Much smaller than
C.	Much more than
D.	Any of these.
Answer» B. Much smaller than

discuss

70.	The piezometric head is the summation of :
A.	Velocity head and pressure head
B.	Pressure head and elevation head
C.	Velocity head and elevation head
D.	None of the above.
Answer» B. Pressure head and elevation head

discuss

71.	The total-energy-line in pipe flow is a graphical representation of the Bernoulli’s equation and represents the sum of velocity head, pressure head and the elevation head above:
A.	The top of the pipeline
B.	The arbitrary horizontal datum
C.	The centre line of pipe
D.	The bottom of the pipe.
Answer» B. The arbitrary horizontal datum

discuss

72.	The total energy represented by the Bernoulli’s equation (p/ρg +V2/2g +z) has the units:
A.	Nm/s
B.	Ns/m
C.	Nm/m
D.	Nm/N.
Answer» D. Nm/N.

discuss

73.	The Bernoulli’s equation written in the conventional form p/ρg + V2/2g + z = constant total energy per unit of certain quantity. Identify this quantity from the choices given below:
A.	Energy per unit mass
B.	Energy per unit weight
C.	Energy per unit volume
D.	Energy per unit specific weight.
Answer» B. Energy per unit weight

discuss

74.	A venturimeter is used for measuring:
A.	Pressure
B.	Flow rate
C.	Total energy
D.	Piezometric head.
Answer» B. Flow rate

discuss

75.	The co-efficient of discharge (Cd) of venturimeter lies within the limits:
A.	0.95 to 0.99
B.	0.8 to 0.85
C.	0.7 to 0.8
D.	0.6 to 0.7
Answer» A. 0.95 to 0.99

discuss

76.	A Pitot-tube is used for measuring:
A.	Velocity of flow
B.	Pressure of flow
C.	Flow rate
D.	Total energy.
Answer» A. Velocity of flow

discuss

77.	When a Pitot-tube is put to use it must be ensured that its alignment is such that:
A.	The horizontal leg should be inclined at 45° in plan
B.	Its horizontal leg is at right angles to the flow direction
C.	Its opening faces upstream and the horizontal leg is perfectly aligned with the direction of flow
D.	None of the above.
Answer» C. Its opening faces upstream and the horizontal leg is perfectly aligned with the direction of flow

discuss

78.	The hydraulic gradient-line indicates the variation of which of the following:
A.	Velocity head in flow direction
B.	Piezometric head in the direction of flow
C.	Total energy of flow in the direction of flow
D.	None of the above.
Answer» B. Piezometric head in the direction of flow

discuss

79.	The momentum correction factor β is used to account for:
A.	Change in direction of flow
B.	Change in total energy
C.	Non-uniform distribution of velocities at inlet and outlet sections
D.	Change in mass rate of flow.
Answer» C. Non-uniform distribution of velocities at inlet and outlet sections

discuss

80.	The change in moment of momentum of fluid due to flow along a curved path results in:
A.	A change in pressure
B.	Torque
C.	A change in the total energy
D.	None of the above.
Answer» B. Torque

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81.	Which of the following is an example of free vortex flow?
A.	A whirlpool in a river
B.	Flow of liquid through a hole provided at the bottom of a container
C.	Flow of liquid around a circular bend in a pipe.
D.	All of the above.
Answer» D. All of the above.

discuss

82.	In case of forced vortex, the rise of liquid level at the ends is .... the fall of liquid level at the axis of rotation.
A.	Less than
B.	More than
C.	Equal to
D.	None of the above
Answer» C. Equal to

discuss

83.	In case of a closed cylindrical vessel sealed at the top and the bottom the volume of air before rotation is ...... the volume of air after:
A.	More than
B.	Less than
C.	Equal to
D.	None of the above
Answer» C. Equal to

discuss

84.	Dimensional analysis is used to
A.	Test the dimensional homogeneity of any equation of fluid motion
B.	Derive rational formulae for a flow phenomenon
C.	Derive equations expressed in terms of non– dimensional parameters
D.	All of the above.
Answer» D. All of the above.

discuss

85.	Which of the following is an advantage of dimensional analysis?
A.	It expresses the functional relationship between the variables in dimensionless terms
B.	In hydraulic model studies it reduces the number of variables involved in a physical phenomenon, generally by three
C.	By the use of dimensional analysis design curves can be developed from experimental data or direct solution of the problem
D.	All of the above.
Answer» D. All of the above.

discuss

86.	dimensionally homogeneous equation is applicable to
A.	C.G.S. system only
B.	F.P.S. system only
C.	M.K.S. and SI systems
D.	All systems of units.
Answer» D. All systems of units.

discuss

87.	In which of the following methods of dimensional analysis, a functional relationship of some variables is expressed in the form of an exponential equation, which must be dimensionally homogeneous?
A.	Buckingham’s π-method
B.	Rayleigh’s method
C.	Bridgman’s method
D.	Matrix–tensor method.
Answer» B. Rayleigh’s method

discuss

88.	In dimensional analysis the Buckingham’s π–theorem is widely used and expresses the resulting equation in terms of
A.	The repeating variables
B.	Geometric, kinematic and dynamic variables
C.	(n – m) dimensionless parameters
D.	n dimensionless parameters.
Answer» C. (n – m) dimensionless parameters

discuss

89.	To apply Buckingham’s π–theorem, m repeating variables are selected from amongst the n variables influencing the phenomenon. The repeating variables are selected such that they
A.	Belong to kinematic and dynamic category of variables
B.	Must always contain the dependent variables
C.	In combination contain each of the m fundamental dimensions involved in the problem.
D.	None of the above.
Answer» C. In combination contain each of the m fundamental dimensions involved in the problem.

discuss

90.	In order that results obtained in model studies correctly represent the behaviour of the prototype, which of the following similarities must be ensured between the model and the prototype?
A.	Geometric similarity
B.	Kinematic similarity
C.	Dynamic similarity
D.	All of the above.
Answer» D. All of the above.

discuss

91.	Dynamic similarity between the model and prototype is the
A.	Similarity of motion
B.	Similarity of lengths
C.	Similarity of forces
D.	None of the above.
Answer» C. Similarity of forces

discuss

92.	...... is equal to the product of shear stress due to viscosity and surface area of flow.
A.	Viscous force
B.	Inertia force
C.	Pressure force
D.	Gravity force.
Answer» A. Viscous force

discuss

93.	Kinematic similarity between model and prototype is the
A.	Similarity of discharge
B.	Similarity of shape
C.	Similarity of streamline pattern
D.	None of the above.
Answer» C. Similarity of streamline pattern

discuss

94.	......... is the ratio of the inertia force to the viscous force.
A.	Froude’s number
B.	Weber’s number
C.	Reynolds number
D.	Mach’s number.
Answer» C. Reynolds number

discuss

95.	........ is the square root of the ratio of the inertia force to the pressure force.
A.	Reynolds number
B.	Mach’s number
C.	Euler’s number
D.	Froude’s number.
Answer» C. Euler’s number

discuss

96.	Euler number is important in which of the following flow situations?
A.	Discharge through orifices, mouthpieces and sluices
B.	Pressure rise due to sudden closure of valves
C.	Flow through pipes
D.	All of the above
Answer» D. All of the above

discuss

97.	Mach’s number is defined as the square root of the ratio of the
A.	Inertia force to the pressure force
B.	Inertia force to the surface tension force
C.	Inertia force to the elastic force
D.	None of the above.
Answer» C. Inertia force to the elastic force

discuss

98.	...... is important in compressible fluid flow problems at high velocities, such as high velocity flow in pipes or motion of high-speed projectiles and missiles.
A.	Euler’s number
B.	Mach’s number
C.	Reynolds number
D.	Froude’s number.
Answer» B. Mach’s number

discuss

99.	Distorted models are required to be prepared for which of the following?
A.	Rivers
B.	Dams across very wide rivers
C.	Harbours
D.	All of the above.
Answer» D. All of the above.

discuss

100.	The scale effect in models can be
A.	Positive only
B.	Negative only
C.	Both positive and negative
D.	None of the above.
Answer» C. Both positive and negative

discuss

730+ Fluid Mechanics and Hydraulic Machines Solved MCQs

High velocity flow in a conduit of large size is known as

If the Reynolds number is less than 2000, the flow in a pipe is

The path followed by fluid particle in motion is called a

A....is an imaginary line within the flow so that the tangent at any point on it indicates the velocity at that point.

A stream line is one

...... is a curve which gives an instantaneous picture of the location of the fluid particles which have passed through a given point.

In fluid mechanics, the continuity equation is a mathematical statement embodying the principle of

An irrational flow is one in which

In a fluid-flow the stream lines are lines

....... is defined mathematically as the line integral of the tangential velocity about a closed path (contour).

The concept of stream function which is based on the principle of continuity is applicable to

The motion is described as ......when the components of rotation or vorticity are zero throughout certain point of the fluid.

........ is defined as a scalar function of space and time such that its negative derivative with respect to any direction gives the fluid velocity in that direction.

If velocity potential (φ) satisfies the Laplace equation, it represents the possible..... flow.

A flow net is a graphical representation of strea lines and equipotential lines such that these lines

Velocity head is given by

Euler’s equation (in differential form) is written as:

In which of the following measuring devices Bernoulli’s equation is used:

The co-efficient of discharge of an orificemeter is ......that of a venturimeter.

The piezometric head is the summation of :

The total-energy-line in pipe flow is a graphical representation of the Bernoulli’s equation and represents the sum of velocity head, pressure head and the elevation head above:

The total energy represented by the Bernoulli’s equation (p/ρg +V2/2g +z) has the units:

The Bernoulli’s equation written in the conventional form p/ρg + V2/2g + z = constant total energy per unit of certain quantity. Identify this quantity from the choices given below:

A venturimeter is used for measuring:

The co-efficient of discharge (Cd) of venturimeter lies within the limits:

A Pitot-tube is used for measuring:

When a Pitot-tube is put to use it must be ensured that its alignment is such that:

The hydraulic gradient-line indicates the variation of which of the following:

The momentum correction factor β is used to account for:

The change in moment of momentum of fluid due to flow along a curved path results in:

Which of the following is an example of free vortex flow?

In case of forced vortex, the rise of liquid level at the ends is .... the fall of liquid level at the axis of rotation.

In case of a closed cylindrical vessel sealed at the top and the bottom the volume of air before rotation is ...... the volume of air after:

Dimensional analysis is used to

Which of the following is an advantage of dimensional analysis?

dimensionally homogeneous equation is applicable to

In which of the following methods of dimensional analysis, a functional relationship of some variables is expressed in the form of an exponential equation, which must be dimensionally homogeneous?

In dimensional analysis the Buckingham’s π–theorem is widely used and expresses the resulting equation in terms of

To apply Buckingham’s π–theorem, m repeating variables are selected from amongst the n variables influencing the phenomenon. The repeating variables are selected such that they

In order that results obtained in model studies correctly represent the behaviour of the prototype, which of the following similarities must be ensured between the model and the prototype?

Dynamic similarity between the model and prototype is the

...... is equal to the product of shear stress due to viscosity and surface area of flow.

Kinematic similarity between model and prototype is the

......... is the ratio of the inertia force to the viscous force.

........ is the square root of the ratio of the inertia force to the pressure force.

Euler number is important in which of the following flow situations?

Mach’s number is defined as the square root of the ratio of the

...... is important in compressible fluid flow problems at high velocities, such as high velocity flow in pipes or motion of high-speed projectiles and missiles.

Distorted models are required to be prepared for which of the following?

The scale effect in models can be