HYDRAULICS AND FLUID MECHANICS OBJECTIVE AND MCQs
Section-6

 

Q61. A jet of water issues from a Nozzle with a velocity 20 m/s and it impinges normally on a flat plate moving away from it at 10 m/s. The cross-sectional area of the jet is 0.01 m2, and the density of water = 1000 kg/m3. The force developed on the plate is

(a) 1000 N 
(b) 100 N 
(c) 10 N 
(d) 2000 N.                                                                                             (GATE-ME-2010)

Ans: (a) 1000 N

 

Q62. The stream function in a two dimensional flow field is given by ψ = x2 – y2. The magnitude of the velocity at point (1, 1) is

 (a) 2

 

\[\text { (b) } 2 \sqrt{2}  \]

 

 (c) 4 
 (d) 8.                                                                                                                        (GATE-ME-1989)

Ans: \[\text { (b) } 2 \sqrt{2}  \]

 

Q63. The specific speed of a turbine is given by

\[(a) N_{s}=\frac{N \sqrt{P}}{H^{3 / 4}} \]

 

\[(b) N_{s}=\frac{N \sqrt{Q}}{H^{3 / 4}} \]

 

\[ (c) N_{s}=\frac{N \sqrt{P}}{H^{5 / 4}}\]

 

\[ (d) N_{s}=\frac{N \sqrt{P}}{H^{3 / 2}}\]

Ans: \[ (c) N_{s}=\frac{N \sqrt{P}}{H^{5 / 4}}\]

 

Q64. The velocity distribution in laminar flow through circular pipe, follows the

(a) parabolic law 
(b) linear law 
(c) logarithmic law 
(d) none of the above.

Ans: (a) parabolic law

Q65. The wetted perimeter P in the above question is given by

(a) P = 2d sec (θ/2)
(b) P = d/2sec θ 
(c) P = d sec 2θ  
(d) P = 2d sec θ.

Ans: (a) P = 2d sec (θ/2)

Q66. The wetted perimeter in a trapezoidal is given by

\[ \text { (a) } P=b+d \sqrt{n^{2}+1}\]

 

\[ \text { (b) } P=2b+d \sqrt{n^{2}+1}\]

 

\[\text { (c) } P=b+2d \sqrt{n^{2}+1} \]

 

\[\text { (d) } P=2b+d \sqrt{n^{2}-1} \]

 

Ans: \[\text { (c) } P=b+2d \sqrt{n^{2}+1} \]

 

Q67. The expressionb (b×d/ b+2d)represents the hydraulic mean depth for

(a) triangular channel 
(b) rectangular channel 
(c) trapezoidal channel 
(d) circular channel 
where b = Width of channel and d = Depth of flow.

Ans: (b) rectangular channel

 

Q68. Chezy’s formula is given by

\[\text { (a) } V=\sqrt{C m i} \]

 

\[\text { (b) } Q=A C \sqrt{m i} \]

 

\[ \text { (C) } Q=C \sqrt{m i}\]

 

(d) m =A/P

where V = Velocity of flow, C = Chezy’s constant,
m = Hydraulic mean depth, and i = Slope of the bed of channel.

\[ \text { (C) } Q=C \sqrt{m i}\] 

 

Q69. The unit discharge (Qu) is given by the expression

\[ \text { (a) } Q_{u}=\frac{Q}{\sqrt{H}}\] 

 

 (b) Qu =Q/H3/2

 

(c) Qu = Q/H3/4

 

 (d) Qu = Q/H5/4

 


Ans: \[ \text { (a) } Q_{u}=\frac{Q}{\sqrt{H}}\]

 

Q70. Unit power (Pu) is given by the expression

\[ \text { (a) } P_{u}=\frac{P}{\sqrt{H}}\] 

 

(b) Pu =PH/3/2

 

(c) Pu =P/H3/4

 

 (d) Pu =P/H5/4 .

 

Ans: (b) Pu =PH/3/2

 

 

 

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Each section contains maximum 80 Questions. To practice more questions visit other sections.
 
Hydraulics and Fluid mechanics MCQ-Section-1

 

Hydraulics and Fluid mechanics MCQ-Section-2

 

Hydraulics and Fluid mechanics MCQ-Section-3

 

Hydraulics and Fluid mechanics MCQ-Section-4

 

Hydraulics and Fluid mechanics MCQ-Section-5

 

Hydraulics and Fluid mechanics MCQ-Section-6 

 


 

 

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