Section-1
HYDRAULICS AND FLUID MECHANICS OBJECTIVE AND MCQs

 

Q71. Ψ = 3x2 – y3 represents a stream function in a two-dimensional flow. The velocity component in ‘x’ direction at the point (1,3) is:                                    SSC JE 2019 Shift-2

(a) 31.5 m/s
(b) 4 m/s
(c) 27 m/s
(d) –24 m/s

Ans: (c) 27 m/s

Ψ = 3x2 – y3
u =-∂Ψ/∂y
u = 3y2
u = 3 × (3)2
u = 27 m/s

Q72. Select the correct statement

(a) Weber’s number is the ratio of inertia force to elastic force.
(b) Weber’s number is the ratio of gravity force to surface tension force.
(c) Weber’s number is the ratio of viscous force to pressure force.
(d) Weber’s number is the ratio of inertia force to surface tension force.

Ans: (d) Weber’s number is the ratio of inertia force to surface tension force.

Q73. Fluid is a substance that

(a) Cannot be subjected to shear forces
(b) Always expands until it fills any container
(c) Has the same shear stress at a point regardless of its motion
(d) Cannot remain at rest under action of any shear force

Ans: (d) Cannot remain at rest under action of any shear force

Q74. The increase in pressure at the outer edge of a drum of radius (r) completely filled up with liquid of density (ρ) and rotating at (ω) rad/s is

(a) ρ ω2 r2
(b) 2ρ ω2 r2
(c) ρ ω2 r2/2
(d) ρ ω2 r2/4

Ans: (c) ρ ω2 r2/2

Q75. A 20 m high dam is filled with water upto the top. The force acting on the vertical dam wall (20 m high × 25 m. wide) is given as (consider density of water = 1000 kg/m3 ; g = acceleration due to gravity):                     SSC JE 2019 Shift-2

(a) 1000 KN
(b) 25,000 N
(c) 5 g MN
(d) 50, 000/g KN

Ans: (c) 5 g MN

Q76. Newton’s law of viscosity is a relationship between

(a) Pressure, velocity and temperature
(b) Shear stress and rate of shear strain
(c) Shear stress and velocity
(d) Rate of shear strain and temperature

Ans: (b) Shear stress and rate of shear strain

Q77. According to Bernoulli’s equation

(a) Z + p/w + v²/2g = constant
(b) Z + p/w – v²/2g = constant
(c) Z – p/w + v²/2g = constant
(d) Z – p/w – v²/2g = constant

Ans: (a) Z + p/w + v²/2g = constant

Q78. Differential 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

Ans: (d) Difference of pressure between two points

Q79. Reynolds number is significant in

(a) Supersonics, as with projectile and jet propulsion
(b) Full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.
(c) Simultaneous motion through two fluids where there is a surface of discontinuity, gravity forces, and wave making effect, as with ship’s hulls
(d) All of the above

Ans: (b) Full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.

Q80. The point in the immersed body through which the resultant pressure of the liquid may be taken to act is known as

(a) Meta center
(b) Center of pressure
(c) Center of buoyancy
(d) Center of gravity

Ans: (b) Center of pressure

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Hydraulics and Fluid mechanics MCQ-Section-1

 

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Hydraulics and Fluid mechanics MCQ-Section-5

 

Hydraulics and Fluid mechanics MCQ-Section-6