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.

151.

The ratio PA PB.(1/2) u0

A. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">[1 + ( /H)] </td></tr></table>
B. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">[1 ( /H)] </td></tr></table>
C. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">[1 (2 /H)] </td></tr></table>
D. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">1 + ( /H)</td></tr></table>
Answer» C. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">[1 (2 /H)] </td></tr></table>
Discussion
152.

The ratio V

A. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">1 2( /H)</td></tr></table>
B. 1
C. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">1 ( /H)</td></tr></table>
D. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">1 + ( /H)</td></tr></table>
Answer» D. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">1 + ( /H)</td></tr></table>
Discussion
153.

Consider steady laminar incompressible axisymmetric fully developed viscous flow through a straight circular pipe of constant crosssectional area at a Reynolds number of 5. The ratio of inertia force to viscous force on a fluid particle is

A. 5
B. 1/5
C. 0
D.
Answer» B. 1/5
Discussion
154.

Water is flowing through a horizontal pipe of constant diameter and the flow is laminar. If the diameter of the pipe is increased by 50% keeping the volume flow rate constant, then the pressure drop in the pipe due to friction will decrease by

A. 33%
B. 50%
C. 70%
D. 80%
Answer» E.
Discussion
155.

The maximum velocity of a one-dimensional incompressible fully developed viscous flow, between two fixed parallel plates, is 6 ms-1. The mean velocity (in ms-1) of the flow is

A. 2
B. 3
C. 4
D. 5
Answer» D. 5
Discussion
156.

The pressure drop for laminar flow of a liquid in a smooth pipe at normal temperature and pressure is

A. directly proportional to density
B. inversely proportional to density
C. Independent of density
D. proportional to (density)
E. <sup>0.75</sup>
Answer» D. proportional to (density)
Discussion
157.

The inlet angle of runner blades of a Francis turbine is 90 . The blades are so shaped that the tangential component of velocity at blade outlet is zero. The flow velocity remains constant through out the blade passage and is equal to half of the blade velocity at runner inlet. The blade efficiency of the runner is

A. 25%
B. 50%
C. 80%
D. 89%
Answer» E.
Discussion
158.

A large hydraulic turbine is to generate 300 kW at 1000 rpm under a head of 40 m. For initial testing, a 1: 4 scale model of the turbine operates under a head of 10 m. The power generated by the model (in kW)will be

A. 2.34
B. 4.68
C. 9.38
D. 18.75
Answer» B. 4.68
Discussion
159.

The head loss for a laminar incompressible flow through a horizontal circular pipe is h

A. 1
B. 4
C. 8
D. 16
Answer» D. 16
Discussion
160.

In a Pelton wheel, the bucket peripheral speed is 10 m/s, the water jet velocity is 25 m/s and volumetric flow rate of the jet is 0.1 m

A. 7.5 kW
B. 15.0 kW
C. 22.5 kW
D. 37.5 kW
Answer» D. 37.5 kW
Discussion
161.

At a hydro electric power plant site, available head and flow rate are 24.5 m and 10.1 m

A. Francis
B. Kaplan
C. Pelton
D. Propeller
Answer» B. Kaplan
Discussion
162.

For laminar flow through along pipe, the pressure drop per unit length increases

A. in linear proportion to the cross-sectional area
B. in proportion to the diameter of the pipe
C. in inverse proportion to the cross-sectional area
D. in inverse proportional to the square of cross-sectional area
Answer» D. in inverse proportional to the square of cross-sectional area
Discussion
163.

In fully developed laminar flow in the circular pipe, the head loss due to friction is directly proportional to _____ (mean velocity/square of the mean velocity)

A. f Mean velocity
B. f = Mean velocity
C. f Mean velocity
D. f = 0
Answer» B. f = Mean velocity
Discussion
164.

Fluid is flowing with an average velocity of V through a pipe of diameter d. Over a length of L,

A. <table><tr><td rowspan="2">f = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>64</center></td></tr><tr><td style="text-align: center;">RE</td></tr></table>
B. <table><tr><td rowspan="2">f = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>64</center></td></tr><tr><td style="text-align: center;">Re</td></tr></table>
C. <table><tr><td rowspan="2">f = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>16</center></td></tr><tr><td style="text-align: center;">Re</td></tr></table>
D. <table><tr><td rowspan="2">f = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>4</center></td></tr><tr><td style="text-align: center;">Re</td></tr></table>
Answer» C. <table><tr><td rowspan="2">f = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>16</center></td></tr><tr><td style="text-align: center;">Re</td></tr></table>
Discussion
165.

Consider steady, incompressible and irrotational flow through a reducer in a horizontal pipe where the diameter is reduced from 20 cm to 10 cm. The pressure in the 20 cm pipe just upstream of the reducer is 150 kPa. The fluid has a vapour pressure of 50 kPa and a specific weight of 5 kN / m

A. 0.05
B. 0.16
C. 0.27
D. 0.38
Answer» C. 0.27
Discussion
166.

Navier Stoke's equation represents the conservation of

A. Energy
B. Mass
C. Pressure
D. Momentum
Answer» E.
Discussion
167.

Bernoulli's equation can be applied between any two points on a stream line for a rotational flow field. State:

A. TRUE
B. FALSE
C. A and B
D. None of these
Answer» B. FALSE
Discussion
168.

The radial component of the fluid acceleration at r = R is

A. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>3V<sup>2</sup>R</center></td></tr><tr><td style="text-align: center;">4h<sup>2</sup></td></tr></table>
B. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>V<sup>2</sup>R</center></td></tr><tr><td style="text-align: center;">4h<sup>2</sup></td></tr></table>
C. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>V<sup>2</sup>R</center></td></tr><tr><td style="text-align: center;">2h<sup>2</sup></td></tr></table>
D. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>V<sup>2</sup>h</center></td></tr><tr><td style="text-align: center;">2R<sup>2</sup></td></tr></table>
Answer» B. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>V<sup>2</sup>R</center></td></tr><tr><td style="text-align: center;">4h<sup>2</sup></td></tr></table>
Discussion
169.

The radial velocity V

A. <table><tr><td rowspan="2">V<sub>r</sub> = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>Vr</center></td></tr><tr><td style="text-align: center;">2h</td></tr></table>
B. <table><tr><td rowspan="2">V<sub>r</sub> = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2Vr</center></td></tr><tr><td style="text-align: center;">h</td></tr></table>
C. <table><tr><td rowspan="2">V<sub>r</sub> = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2Vh</center></td></tr><tr><td style="text-align: center;">r</td></tr></table>
D. <table><tr><td rowspan="2">V<sub>r</sub> = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>Vh</center></td></tr><tr><td style="text-align: center;">r</td></tr></table>
Answer» B. <table><tr><td rowspan="2">V<sub>r</sub> = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2Vr</center></td></tr><tr><td style="text-align: center;">h</td></tr></table>
Discussion
170.

In a steady flow through a nozzle, the flow velocity on the nozzle axis is given by v = u

A. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>L</center></td></tr><tr><td style="text-align: center;">u<sub>0</sub></td></tr></table>
B. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>L</center></td><td rowspan="2">ln4</td></tr><tr><td style="text-align: center;">3u<sub>0</sub></td></tr></table>
C. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>L</center></td></tr><tr><td style="text-align: center;">4u<sub>0</sub></td></tr></table>
D. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>L</center></td></tr><tr><td style="text-align: center;">2.5u<sub>0</sub></td></tr></table>
Answer» C. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>L</center></td></tr><tr><td style="text-align: center;">4u<sub>0</sub></td></tr></table>
Discussion
171.

A leaf is caught in a whirlpool. At a given instant, the leaf is at a distance of 120 m from the centre of the whirlpool. The whirlpool can be described by the following velocity distribution:

A. 48 m
B. 64 m
C. 120 m
D. 142 m
Answer» C. 120 m
Discussion
172.

The velocity components in the x and y directions of a two dimensional potential flow are u and v, respectively.

A. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center> v</center></td></tr><tr><td style="text-align: center;"> x</td></tr></table>
B. <table><tr><td rowspan="2">-</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center> v</center></td></tr><tr><td style="text-align: center;"> x</td></tr></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></tr><tr><td style="text-align: center;"> y</td></tr></table>
D. <table><tr><td rowspan="2">-</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center> v</center></td></tr><tr><td style="text-align: center;"> y</td></tr></table>
Answer» E.
Discussion
173.

The velocity components in the x and y directions are given by u = xy

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;">4</td></tr></table>
B. <table><tr><td rowspan="2">-</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>4</center></td></tr><tr><td style="text-align: center;">3</td></tr></table>
C. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>4</center></td></tr><tr><td style="text-align: center;">3</td></tr></table>
D. 3
Answer» E.
Discussion
174.

Circulation is defined as line integral of tangential component of velocity about a _______ (fill in the blanks)

A. In a flow field
B. closed contour exists.
C. A and B
D. None of these
Answer» D. None of these
Discussion
175.

A fluid is one which can be defined as a substance that

A. has that same shear stress at all points
B. can deform indefinitely under the action of the smallest shear force
C. has the small shear stress in all directions
D. is practically incompressible
Answer» C. has the small shear stress in all directions
Discussion
176.

A fluid is said to be Newtonian fluid when the shear stress is

A. directly proportional to the velocity gradient
B. inversely proportional to the velocity gradient
C. independent of the velocity gradient
D. none of these
Answer» B. inversely proportional to the velocity gradient
Discussion