Explore topic-wise MCQs in Fluid Mechanics and Hydraulic Machinery.

This section includes 176 Mcqs, each offering curated multiple-choice questions to sharpen your Fluid Mechanics and Hydraulic Machinery knowledge and support exam preparation. Choose a topic below to get started.

101.

The velocity profile inside the boundary layer for flow over a plate is given as (u / u

A. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2</center></td><td rowspan="2"></td></tr><td align="center"> </td></table>
B. <table><tr><td rowspan="2">1 -</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2</center></td><td rowspan="2"></td></tr><td align="center"> </td></table>
C. <table><tr><td rowspan="2">1 +</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2</center></td><td rowspan="2"></td></tr><td align="center"> </td></table>
D. 0
Answer» C. <table><tr><td rowspan="2">1 +</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2</center></td><td rowspan="2"></td></tr><td align="center"> </td></table>
Discussion
102.

The parameters which determines the friction factor for turbulent flow in a rough pipe are

A. Froude number and relative roughness
B. Froude number and Mach number
C. Reynolds number and relative roughness
D. Mach number and relative roughness
Answer» D. Mach number and relative roughness
Discussion
103.

If the fluid velocity for a potential flow is given by V(x, y) = u(x, y)i + v(x, y)j with usual notations, then the slope of the potential line at (x, y) is

A. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>v</center></td><td rowspan="2"></td></tr><td align="center">u</td></table>
B. <table><tr><td rowspan="2">-</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>u </center></td><td rowspan="2"></td></tr><td align="center">v</td></table>
C. <table><tr><td rowspan="2">-</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>v</center></td><td rowspan="2"></td></tr><td align="center">u </td></table>
D. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>u</center></td><td rowspan="2"></td></tr><td align="center">v</td></table>
Answer» C. <table><tr><td rowspan="2">-</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>v</center></td><td rowspan="2"></td></tr><td align="center">u </td></table>
Discussion
104.

Consider a velocity field V K(yi + xk), where K is a constant. The vorticity, &ohm; Z, is

A. K
B. K
C. K/2
D. K/2
Answer» B. K
Discussion
105.

Water (density = 1000 kg/m

A. 100 Watt
B. 150 Watt
C. 50 Watt
D. 200 Watt
Answer» B. 150 Watt
Discussion
106.

Consider the following statements regarding streamline(s):

A. (i), (ii), (iv)
B. (ii), (iii), (iv)
C. (i), (iii), (iv)
D. (i), (ii), (iii)
Answer» E.
Discussion
107.

A cube of side 100 mm is placed at the bottom of an empty container on one of its faces. The density of the material of the cube is 800 kg/m

A. h 80 mm
B. h 70 mm
C. h 75 mm
D. h 81 mm
Answer» B. h 70 mm
Discussion
108.

For a certain two-dimensional incompressible flow, velocity field is given by 2xyi y j. The streamlines for this flow are given by the family of curves

A. x y = constant
B. xy = constant
C. 2xy y = constant
D. xy constant
Answer» C. 2xy y = constant
Discussion
109.

Water is coming out from a tap and a falls vertically downwards. At the tap opening, the stream diameter is 20 mm with uniform velocity of 2 m/s. Acceleration due to gravity is 9.81 m/ s . Assuming steady, inviscid flow, constant atmospheric pressure everywhere and neglecting curvature and surface tension effects, the diameter in mm of the stream 0.5 m below the tap is approximately

A. 10
B. 15
C. 20
D. 25
Answer» C. 20
Discussion
110.

A water container is kept on a weighing balance. Water from a tap is falling vertically into the container with a volume flow rate of Q; the velocity of the water when it hits the water surface is U. At a particular instant of time the total mass of the container and water is m. The force registered by the weighing balance at this instant of time is

A. mg + QU
B. mg + 2 QU
C. mg + QU /2
D. QU /2
Answer» B. mg + 2 QU
Discussion
111.

The necessary and sufficient condition which brings about separation of boundary layer is

A. True
B. False
C. NA
D. NA
Answer» B. False
Discussion
112.

The predominant forces acting on an element of fluid in the boundary layer over a flat plate in a uniform parallel stream are

A. Viscous and pressure forces
B. Viscous and inertia forces
C. Viscous and body forces
D. Inertial and pressure forces
Answer» C. Viscous and body forces
Discussion
113.

A venturimeter of 20 mm throat diameter is used to measure the velocity of water in a horizontal pipe of 40 mm diameter. If the pressure difference between the pipe and throat sections is found to be 30 kPa then, neglecting frictional losses, the flow velocity is

A. 0.2 m/s
B. 1.0 m/s
C. 1.4 m/s
D. 2.0 m/s
Answer» E.
Discussion
114.

In a venturimeter, the angle of the diverging section is more than that of converging section. State: (T/F)

A. False
B. True
C. &true and False
D. None of these
Answer» B. True
Discussion
115.

The instantaneous stream wise velocity of a turbulent flow is given as follows: u(x, y, z, t) =

A. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>u'</center></td><td rowspan="2"></td></tr><td align="center">2</td></table>
B.
C. <table><tr><td rowspan="2">-</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center><span style=" text-decoration: overline;">u</span></center></td><td rowspan="2"></td></tr><td align="center">2</td></table>
D. zero
E. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center><span style=" text-decoration: overline;">u</span></center></td><td rowspan="2"></td></tr><td align="center">2</td></table>
Answer» D. zero
Discussion
116.

A two-dimensional incompressible frictionless flow field is given by = xi - yj. If is the density of the fluid, the expression for pressure gradient vector at any point in the flow field is given as

A. (xi - yj)
B. (xi + yj)
C. - (x i + y j)
D. - (xi + yj)
Answer» E.
Discussion
117.

Flow separations flow past a solid object is caused by

A. A reduction of pressure to vapour pressure
B. A negative pressure gradient
C. A positive pressure gradient
D. The boundary layer thickness reducing to zero
Answer» D. The boundary layer thickness reducing to zero
Discussion
118.

The velocity field of an incompressible flow is given by V = (a

A. 2
B. 1
C. 3
D. 0
Answer» B. 1
Discussion
119.

A test is conducted on a one-fifth scale model of a Francis turbine under a head of 2 m and volumetric flow rate of 1 m

A. 29.25
B. 30.26
C. 29.05
D. 29
Answer» D. 29
Discussion
120.

An aluminium alloy (density 2600 kg/m

A. 7.7 N.
B. 8.7 N.
C. 6.7 N.
D. 9.7 N.
Answer» B. 8.7 N.
Discussion
121.

For a completely submerged body with centre of gravity G and centre of buoyancy B, the condition of stability will be

A. G is located below B
B. G is located above B
C. G and B are coincident
D. Independent of the locations of G and B
Answer» B. G is located above B
Discussion
122.

For steady flow of a vlscous In compressible fluid through pipe of constant of diameter, the average veloolty In the fully developed region is constant, Which one of the following statements about the average velocity in the developing region is TRUE?

A. It increases until the flow is fully developed,
B. (b)
C. It is constant and is equal to the average velocity in the fully developed region,
D. It decreases until the flow is fully developed.
E. It is constant but is always lower than the average velocity in the fully developed region,
Answer» C. It is constant and is equal to the average velocity in the fully developed region,
Discussion
123.

For the continuity equation given by . V = 0 to be valid, where V is the velocity vector, which one of the following is a necessary condition?

A. Steady flow
B. Irrotational flow
C. Inviscid flow
D. Incompressible flow
Answer» E.
Discussion
124.

Which combination of the following statements about steady incompressible forced vortex flow is correct?

A. P and Q
B. R and S
C. P and R
D. P and S
Answer» C. P and R
Discussion
125.

The 2-D flow with, velocity

A. Compressible and irrotational
B. Compressible and not irrotational
C. In compressible and irrotational
D. In compressible and not irrotational
Answer» E.
Discussion
126.

For an in-compressible flow field, V, which one of the following conditions must be satisfied?

A. . V = 0
B. V = 0
C. (V . ) V = 0
D. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center> V </center></td><td rowspan="2">(V . ) V = 0 </td></tr><td align="center"> t</td></table>
Answer» B. V = 0
Discussion
127.

In a Lagrangian system, the position of a fluid particle in a flow is described as x = x

A. unsteady and one-dimensional
B. steady and two-dimensional
C. steady and one-dimensional
D. unsteady and two-dimensional
Answer» C. steady and one-dimensional
Discussion
128.

A circular plate 1 m in diameter is submerged vertically in water such its upper edge is 8 m below the free surface of water. The total hydro static pressure force on one side of plate is

A. 6.7 kN
B. 65.4 kN
C. 45.0 kN
D. 77.0 kN
Answer» C. 45.0 kN
Discussion
129.

If there are m physical quantities and n fundamental dimensions in a particular process, the number of non-dimensional parameters is

A. m + n
B. m n
C. m n
D. m/n
Answer» D. m/n
Discussion
130.

As the transition from laminar to turbulent flow is induced in a cross flow past a circular cylinder the value of the drag coefficient drops.

A. False
B. True
C. Neither True nor False
D. None of these
Answer» C. Neither True nor False
Discussion
131.

For a fully developed flow through a pipe, the ratio of the maximum velocity to the average velocity is _________(fill in the blanks)

A. Two
B. Three
C. Zero
D. None of these
Answer» B. Three
Discussion
132.

The discharge in m

A. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>3 </center></td></tr><tr><td style="text-align: center;">50</td></tr></table>
B. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>3 </center></td></tr><tr><td style="text-align: center;">2500</td></tr></table>
C. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>3 </center></td></tr><tr><td style="text-align: center;">5000</td></tr></table>
D. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>3 </center></td></tr><tr><td style="text-align: center;">10000</td></tr></table>
Answer» E.
Discussion
133.

Assuming ideal flow, the force F in newtons required on the plunger to push out the water is

A. 0
B. 0.04
C. 0.13
D. 1.15
Answer» C. 0.13
Discussion
134.

Water flows through a 10 mm diameter and 250 m long smooth pipe at an average velocity of 0.1 m/s. The density and the viscosity of water are 997 kg/m

A. 6840 pascal
B. 680 pascal
C. 4844 pascal
D. 9840 pascal
Answer» B. 680 pascal
Discussion
135.

Oil flows through a 200 mm diameter horizontal cast iron pipe (friction factor, f = 0.0225) of length 500 m, The volumetric flow rate is 0.2 m

A. 116.18
B. 0.116
C. 18.22
D. 232.36
Answer» B. 0.116
Discussion
136.

A smooth pipe of diameter 200 mm carries water. The pressure in the pipe at section S1 (elevation: 10 m) ie 50 kPa, At section S2 (elevation: 12 m) the pressure is 20 kPa and velocity is 2 m/s. Density of water is 1000 kg/m

A. flow is from S1 to S2 and head loss is 0.53 m
B. flow is from S2 to S1 and head loss is 0.53 m
C. flow is from S1 to S2 and head loss is 1.06 m
D. flow is from S2 to S1 and head loss is 1.06 m
Answer» D. flow is from S2 to S1 and head loss is 1.06 m
Discussion
137.

Neglect losses in the cylinder and assume fully developed laminar viscous flow throughout the needle: the Darcy friction factor is 64/Re. where Re is the Reynolds number. Given that the viscosity of water is 1.0 10

A. 0.13
B. 0.16
C. 0.3
D. 4.4
Answer» D. 4.4
Discussion
138.

Kaplan turbine is

A. A high head mixed flow turbine
B. A low head axial flow turbine
C. An outward flow reaction turbine
D. An impulse inward flow turbine
Answer» C. An outward flow reaction turbine
Discussion
139.

Specific speed of a Kaplan turbine ranges between

A. 30 to 60
B. 60 to 300
C. 300 to 600
D. 600 to 1000
Answer» E.
Discussion
140.

Cavitation in a hydraulic reaction turbine is most likely to occur at the turbine

A. Entry
B. Exit
C. Stator exit
D. Rotor exit
Answer» E.
Discussion
141.

A fluid of dynamic viscosity 2 10

A. 180 Pa/m
B. 1.8208 Pa/m
C. 182.08 Pa/m
D. 18208 Pa/m
Answer» C. 182.08 Pa/m
Discussion
142.

A hydraulic turbine develops 1000 kW power for a head of 40 m. If the head is reduced to 20 m, the power developed (in kW) is

A. 177
B. 354
C. 500
D. 707
Answer» C. 500
Discussion
143.

If P is the gauge pressure within a spherical droplet, then gauge pressure within a bubble of the same fluid and of same size will be

A. P/4
B. P/2
C. P
D. 2P
Answer» E.
Discussion
144.

Oil in a hydraulic cylinder is compressed from an initial volume 2 m

A. 1000 MPa
B. 2000 MPa
C. 4000 MPa
D. 8000 MPa
Answer» C. 4000 MPa
Discussion
145.

For a fluid element in a two dimensional flow field (x-y plane), if it will undergo

A. Translation only
B. Translation and rotation
C. Translation and deformation
D. Deformation only
Answer» D. Deformation only
Discussion
146.

Streamlines, path lines and streak lines are virtually identical for

A. Uniform flow
B. Flow of ideal fluids
C. Steady flow
D. Non uniform flow
Answer» D. Non uniform flow
Discussion
147.

A velocity field is given as

A. (ii)
B. (i)
C. (i) and (ii)
D. (iii)
Answer» B. (i)
Discussion
148.

The velocity profile in fully developed laminar flow in a pipe of diameter D is given by u = u

A. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center> u<sub>0</sub>L</center></td></tr><tr><td style="text-align: center;">D </td></tr></table>
B. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>4 u<sub>0</sub>L</center></td></tr><tr><td style="text-align: center;">D </td></tr></table>
C. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>8 u<sub>0</sub>L</center></td></tr><tr><td style="text-align: center;">D </td></tr></table>
D. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>16 u<sub>0</sub>L</center></td></tr><tr><td style="text-align: center;">D </td></tr></table>
Answer» E.
Discussion
149.

Two pipes of uniform section but different diameters carry water at the same flow rate. Water properties are the same in the two pipes. The Reynolds number, based on the pipe diameter

A. if the same in the both pipes
B. is large in then arrow pipe
C. is smaller in the narrower pipe
D. depends on the pipe material
Answer» C. is smaller in the narrower pipe
Discussion
150.

Oil is being pumped through a straight pipe, the pipe length, diameter and volumetric flow rate are all doubled in a new arrangement. The pipe friction factor, however, remains constant. The ratio of pipe frictional losses in the new arrangement to that in the original configuration would be

A. 1/4
B. 1/2
C. 2
D. 4
Answer» B. 1/2
Discussion