1080+ Fluid Mechanics (FM) Solved MCQs

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

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101.	Drag force is affected by__________
A.	Cross sectional area and smoothness
B.	Rigidity and density
C.	Pressure and temperature
D.	Mass
Answer» A. Cross sectional area and smoothness
Explanation: Drag force is affected by cross sectional area and smoothness. If it is affected by cross sectional area, then it is called form drag. If it is affected by surface smoothness, then it is called as surface drag.

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102.	The lift force acts in _____ to the flow velocity.
A.	Perpendicular direction
B.	Same direction
C.	Opposite direction
D.	Different directions
Answer» A. Perpendicular direction
Explanation: The lift force acts in the perpendicular direction to that of the relative flow velocity. It acts in the perpendicular direction with respect to a surrounding fluid flow. Thus, option Perpendicular direction is correct.

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103.	Which among the following is the correct formula for drag?
A.	D = Cd * A * 0.5 * r * V2
B.	D = Cd * A * 0.5 * r * V*2
C.	D = Cd * A * 0.5 * r * V/2
D.	D = 0.5 * r * V
Answer» A. D = Cd * A * 0.5 * r * V2
Explanation: The drag force acts in the opposite direction to that of the relative flow velocity. It acts in the opposite direction with respect to a surrounding fluid flow. Thus, the correct option is D = Cd * A * 0.5 * r * V2.

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104.	Which among the following is the correct formula for lift?
A.	D = Cl * A * 0.5 * r * V2
B.	D = Cl * A * 0.5 * r * V*2
C.	D = Cl * A * 0.5 * r * V/2
D.	D = 0.5 * r * V
Answer» A. D = Cl * A * 0.5 * r * V2
Explanation: The lift force is a force that acts in the perpendicular direction to that of the relative flow velocity. It acts in the perpendicular direction with respect to a surrounding fluid flow. Thus, the correct option is D = Cl * A * 0.5 * r * V2.

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105.	A flow in which the viscosity of fluid is dominating over the inertia force is called
A.	Steady flow
B.	Unsteady flow
C.	Laminar flow
D.	Turbulent flow
Answer» C. Laminar flow

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106.	The celerity (velocity) of a pressure wave in a fluid is given by (where K = Bulk modulus, and ρ = Density of the fluid)
A.	K.ρ
B.	K/ρ
C.	ρ/K
D.	None of these
Answer» B. K/ρ

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107.	A fluid having no viscosity is known as
A.	Real fluid
B.	Ideal fluid
C.	Newtonian fluid
D.	Non-Newtonian fluid
Answer» B. Ideal fluid

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108.	In order to avoid tendency of separation at throat in a Venturimeter, the ratio of the diameter at throat to the diameter of pipe should be
A.	1/16 to 1/8
B.	1/8 to 1/4
C.	1/4 to 1/3
D.	1/3 to 1/2
Answer» D. 1/3 to 1/2

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109.	Liquids transmit pressure equally in all the directions. This is according to
A.	Boyle's law
B.	Archimedes principle
C.	Pascal's law
D.	Newton's formula
Answer» C. Pascal's law

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110.	The discharge over a triangular notch is
A.	Inversely proportional to H3/2
B.	Directly proportional to H3/2
C.	Inversely proportional to H5/2
D.	Directly proportional to H5/2
Answer» D. Directly proportional to H5/2

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111.	A flow whose streamline is represented by a straight line, is called __________ dimensional flow.
A.	One
B.	Two
C.	Three
D.	Four
Answer» A. One

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112.	The body will float if the force of buoyancy is __________ the weight of the liquid displaced.
A.	Equal to
B.	Less than
C.	More than
D.	None of these
Answer» C. More than

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113.	The density of water is 1000 kg/m3 at
A.	0° C
B.	0° K
C.	4° C
D.	20° C
Answer» C. 4° C

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114.	Bulk modulus of a fluid __________ as the pressure increases.
A.	Remain same
B.	Decreases
C.	Increases
D.	None of these
Answer» C. Increases

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115.	The coefficient of viscosity may be determined by
A.	Capillary tube method
B.	Orifice type viscometer
C.	Rotating cylinder method
D.	All of these
Answer» D. All of these

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116.	According to Newton's law of viscosity, the shear stress on a layer of a fluid is __________ to the rate of shear strain.
A.	Equal to
B.	Directly proportional
C.	Inversely proportional
D.	None of these
Answer» B. Directly proportional

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117.	A vessel of 4 m3 contains oil which weighs 30 kN. The specific weight of the oil is
A.	4.5 kN/m3
B.	6 kN/m3
C.	7.5 kN/m3
D.	10 kN/m3
Answer» C. 7.5 kN/m3

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118.	The increase of temperature results in
A.	Increase in viscosity of gas
B.	No changes in viscosity of liquid
C.	Decrease in viscosity of gas
D.	Decrease in viscosity of liquid
Answer» D. Decrease in viscosity of liquid

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119.	A manometer is used to measure
A.	Low pressure
B.	Moderate pressure
C.	High pressure
D.	Atmospheric pressure
Answer» C. High pressure

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120.	Which of the following meters is not associated with viscosity?
A.	Red wood
B.	Say bolt
C.	Engler
D.	Orsat
Answer» D. Orsat

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121.	The specific weight of water in S.I. units is taken as
A.	9.81 kN/m3
B.	9.81 × 103 N/m3
C.	9.81 × 10-6 N/mm3
D.	Any one of these
Answer» D. Any one of these

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122.	Manometer is used to measure
A.	Pressure in pipes, channels etc.
B.	Atmospheric pressure
C.	Very low pressure
D.	Difference of pressure between two points
Answer» A. Pressure in pipes, channels etc.

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123.	The flow in which conditions do not change with time at any point, is known as
A.	One dimensional flow
B.	Uniform flow
C.	Steady flow
D.	Turbulent flow
Answer» C. Steady flow

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124.	A nozzle placed at the end of a water pipe line discharges water at a
A.	Low pressure
B.	High pressure
C.	Low velocity
D.	High velocity
Answer» D. High velocity

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125.	The pressure of fluid due to hammer blow is
A.	Directly proportional to density of fluid
B.	Inversely proportional to density of fluid
C.	Directly proportional to (density)1/2 of fluid
D.	Inversely proportional to (density)1/2 of fluid
Answer» C. Directly proportional to (density)1/2 of fluid

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126.	In order to measure the flow with a Venturimeter, it is installed in
A.	Horizontal line
B.	Inclined line with flow upwards
C.	Inclined line with flow downwards
D.	Any direction and in any location
Answer» D. Any direction and in any location

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127.	If mercury in a barometer is replaced by water, the height of 3.75 cm of mercury will be following cm of water
A.	51 cm
B.	50 cm
C.	52 cm
D.	52.2 cm
Answer» A. 51 cm

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128.	According to equation of continuity,
A.	w1a1 = w2a2
B.	w1v1 = w2v2
C.	a1v1 = a2v2
D.	a1/v1 = a2/v2
Answer» C. a1v1 = a2v2

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129.	One poise is equal to
A.	0.1 N-s/m2
B.	1 N-s/m2
C.	10 N-s/m2
D.	100 N-s/m2
Answer» A. 0.1 N-s/m2

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130.	When a vertical wall is subjected to pressures due to liquid on both sides, the resultant pressure is the __________ of the two pressures.
A.	Sum
B.	Difference
C.	Arithmetic mean
D.	Geometric mean
Answer» B. Difference

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131.	The mercury does not wet the glass. This is due to the property of the liquid known as
A.	Cohesion
B.	Adhesion
C.	Viscosity
D.	Surface tension
Answer» D. Surface tension

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132.	When the pressure intensity at a point is more than the local atmospheric pressure, then the difference of these two pressures is called
A.	Gauge pressure
B.	Absolute pressure
C.	Positive gauge pressure
D.	Vacuum pressure
Answer» C. Positive gauge pressure

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133.	A pipe of length more than double the diameter of orifice fitted externally or internally to the orifice is called a
A.	Notch
B.	Weir
C.	Mouthpiece
D.	Nozzle
Answer» C. Mouthpiece

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134.	An open tank containing liquid is moving with an acceleration on an inclined plane. The inclination of the free surface of the liquid will be __________ to the acceleration of the tank.
A.	Equal to
B.	Directly proportional
C.	Inversely proportional
D.	None of these
Answer» B. Directly proportional

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135.	One stoke is equal to
A.	10-2 m2/s
B.	10-3 m2/s
C.	10-4 m2/s
D.	10-6 m2/s
Answer» C. 10-4 m2/s

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136.	Falling drops of water become spheres due to the property of
A.	Surface tension of water
B.	Compressibility of water
C.	Capillarity of water
D.	Viscosity of water
Answer» A. Surface tension of water

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137.	The specific gravity of an oil whose specific weight is 7.85 kN/m3, is
A.	0.8
B.	1
C.	1.2
D.	1.6
Answer» A. 0.8

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138.	The length of the divergent cone in a Venturimeter is __________ that of the convergent cone.
A.	Equal to
B.	Double
C.	Three to four times
D.	Five to six times
Answer» C. Three to four times

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139.	The stress-strain relation of the Newtonian fluid is
A.	Linear
B.	Parabolic
C.	Hyperbolic
D.	Inverse type
Answer» A. Linear

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140.	The viscosity of a liquid __________ its rate of flow through a hole in a vessel.
A.	Effects
B.	Does not effect
C.	Both A and B
D.	None of these
Answer» A. Effects

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141.	The unit of surface tension is
A.	N/m
B.	N/m2
C.	N/m3
D.	N-m
Answer» A. N/m

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142.	The units of dynamic or absolute viscosity are
A.	Metres² per sec
B.	kg sec/meter
C.	Newton-sec per meter
D.	Newton-sec² per meter
Answer» C. Newton-sec per meter

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143.	A flow in which the volume of a fluid and its density does not change during the flow is called _________ flow.
A.	Incompressible
B.	Compressible
C.	Viscous
D.	None of these
Answer» A. Incompressible

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144.	The weight per unit volume of a liquid at a standard temperature and pressure is called
A.	Specific weight
B.	Mass density
C.	Specific gravity
D.	None of these
Answer» A. Specific weight

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145.	The flow of water through the hole in the bottom of a wash basin is an example of
A.	Steady flow
B.	Uniform flow
C.	Free vortex
D.	Forced vortex
Answer» C. Free vortex

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146.	A flow whose streamline is represented by a curve, is called
A.	One-dimensional flow
B.	Two-dimensional flow
C.	Three-dimensional flow
D.	Four-dimensional flow
Answer» B. Two-dimensional flow

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147.	The value of coefficient of discharge is __________ the value of coefficient of velocity.
A.	Less than
B.	Same as
C.	More than
D.	None of these
Answer» A. Less than

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148.	A fluid whose viscosity does not change with the rate of deformation or shear strain is known as
A.	Real fluid
B.	Ideal fluid
C.	Newtonian fluid
D.	Non-Newtonian fluid
Answer» B. Ideal fluid

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149.	Flow occurring in a pipeline when a valve is being opened is
A.	Steady
B.	Unsteady
C.	Laminar
D.	Vortex
Answer» B. Unsteady

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150.	The water pressure per metre length on a vertical masonry wall of dam is (where w = Specific weight of the liquid, and H = Height of the liquid)
A.	wH/2
B.	wH
C.	wH2/2
D.	wH2/4
Answer» C. wH2/2

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1080+ Fluid Mechanics (FM) Solved MCQs

Drag force is affected by__________

The lift force acts in _____ to the flow velocity.

Which among the following is the correct formula for drag?

Which among the following is the correct formula for lift?

A flow in which the viscosity of fluid is dominating over the inertia force is called

The celerity (velocity) of a pressure wave in a fluid is given by (where K = Bulk modulus, and ρ = Density of the fluid)

A fluid having no viscosity is known as

In order to avoid tendency of separation at throat in a Venturimeter, the ratio of the diameter at throat to the diameter of pipe should be

Liquids transmit pressure equally in all the directions. This is according to

The discharge over a triangular notch is

A flow whose streamline is represented by a straight line, is called __________ dimensional flow.

The body will float if the force of buoyancy is __________ the weight of the liquid displaced.

The density of water is 1000 kg/m3 at

Bulk modulus of a fluid __________ as the pressure increases.

The coefficient of viscosity may be determined by

According to Newton's law of viscosity, the shear stress on a layer of a fluid is __________ to the rate of shear strain.

A vessel of 4 m3 contains oil which weighs 30 kN. The specific weight of the oil is

The increase of temperature results in

A manometer is used to measure

Which of the following meters is not associated with viscosity?

The specific weight of water in S.I. units is taken as

Manometer is used to measure

The flow in which conditions do not change with time at any point, is known as

A nozzle placed at the end of a water pipe line discharges water at a

The pressure of fluid due to hammer blow is

In order to measure the flow with a Venturimeter, it is installed in

If mercury in a barometer is replaced by water, the height of 3.75 cm of mercury will be following cm of water

According to equation of continuity,

One poise is equal to

When a vertical wall is subjected to pressures due to liquid on both sides, the resultant pressure is the __________ of the two pressures.

The mercury does not wet the glass. This is due to the property of the liquid known as

When the pressure intensity at a point is more than the local atmospheric pressure, then the difference of these two pressures is called

A pipe of length more than double the diameter of orifice fitted externally or internally to the orifice is called a

An open tank containing liquid is moving with an acceleration on an inclined plane. The inclination of the free surface of the liquid will be __________ to the acceleration of the tank.

One stoke is equal to

Falling drops of water become spheres due to the property of

The specific gravity of an oil whose specific weight is 7.85 kN/m3, is

The length of the divergent cone in a Venturimeter is __________ that of the convergent cone.

The stress-strain relation of the Newtonian fluid is

The viscosity of a liquid __________ its rate of flow through a hole in a vessel.

The unit of surface tension is

The units of dynamic or absolute viscosity are

A flow in which the volume of a fluid and its density does not change during the flow is called _________ flow.

The weight per unit volume of a liquid at a standard temperature and pressure is called

The flow of water through the hole in the bottom of a wash basin is an example of

A flow whose streamline is represented by a curve, is called

The value of coefficient of discharge is __________ the value of coefficient of velocity.

A fluid whose viscosity does not change with the rate of deformation or shear strain is known as

Flow occurring in a pipeline when a valve is being opened is

The water pressure per metre length on a vertical masonry wall of dam is (where w = Specific weight of the liquid, and H = Height of the liquid)