Wednesday, 29 January 2020

# Fluid Mechanics Online Test for Competitive Exams-GATE

Fluid Mechanics Online Test for Competitive Exams-GATE:The questions which comes under the concept of Fluid Mechanica and Hydraulic Machinery are presented below and the rest will be updated soon.

Questions-1 Mark:

1.The hydrostatic force on one side of a submerged surface of unit area with centroid 3m below the free surface of the liquid is

(Note:Where γ is Unit Weight of the liquid in Newton per cubic metre.)

1. Equal to 3γ
2. less than 3γ
3. 3γ times depth of center of pressure
4. Equal to 2γ

Ans: a

2.One pipe system is said to be equivalent to another when the following quantifies are the same

1. hL ,Re
2. f,Q
3. hL ,Q
4. a,L/D

Ans: c

3.The pressure at the throat of Venturimeter is

1. Never be greater than the vapour pressure of the flowing fluid
2. Always less than the atmospheric pressure
3. Function of throat to inlet area ratio
4. Greater than the inlet pressure if the Venturi is kept inclined upwards

Ans: b

4.Surface tension of a fluid is zero

1. When the fluid is at rest
2. Inversely proportional to fluid mass density
3. The result of interaction between
4. Depend on the forces of molecular attraction

Ans: d

5.A fluid is said to be the irrotational when

1. Fluid has zero vorticity.
2. Flow is both steady and uniform
3. Fluid obeys Newton’s law of viscosity
4. Shear stress varies linearly across the section.

Ans: a

6.The normal stress is the same on all the planes at any point in a fluid only when the fluid is

1. At rest
2. Ideal and is in motion
3. Frictionless
4. In motion

Ans: a

7.A 1:10 Reduced scale model of a water turbine runs at the same speed as the prototype turbine.The ratio of Prototype to model turbine discharges should be

1. 10
2. 1
3. 1000
4. 100

Ans: c

8.All the terms of Bernoulli’s equation:(ρ/r)+(V2/2g)+Z =Constant have the units of

1. Force per unit mass
2. Work for unit acceleration
3. Work per Unit Weight
4. Energy per unit mass

Ans: c

9.The power dissipated in a light loaded viscous fluid lubricated bearing at ‘N’ r.p.m. is 1 kilowatt.The power dissipated at 2N r.p.m. would be

1. 2 Kw
2. 4 Kw
3. 12 Kw
4. 16 Kw

Ans: b

10.The thickness of laminar boundary layer on that plate is 2 cm at x = L/2.The thickness at x = L is

1. 4.71 cm
2. 2.828 cm
3. 4.414 cm
4. 1.414 cm

Ans: b

Questions-2 Marks:

11.A plane lamina in the form of a hollow circle of outer and inner diameters 2 m and 1 m respectively is immersed in a liquid of specific gravity 0.878 such that its extreme edges are at depths of 1.20 m and 2.2 m below the free surface.The hydrostatic force on one side of lamina,in KN is

1. 69
2. 103.5
3. 34.5
4. 138.5

Ans: c

12.The velocity field in a 3-D is given by u=-x;v=2y and w=(3-z).The equation of the stream line that passes through a point (1,1,1) is

1. x=(1/(y))Power(0.5) =(3-z)/2
2. x2=y2=(z/2)
3. x2=(1/y)=z
4. x=y2=z

Ans: a

13.Two pipes carrying water and Nitro-benzene are connected by a Mercury differential gauge as shown in figure.The difference in pressure (P1-P2),in kPa is

1. 101
2. 60
3. 210
4. 202

Ans: d

14.The change in moment of momentum of fluid due to flow along with curved path results in

1. a Torque
2. A change in pressure
3. A change in kinetic energy of Jet
4. A dynamic force which passes through the centre of

Ans: a

15.A Bush Bearing of length 30 cm and diameter 18.01 cm supports a shaft of 18 cm diameter. The shaft rotates at 36.65 rad/sec.The viscosity of the lubricant is 1.96 poise.The Power dissipated in the bearing,in kW,is

1. 14.46
2. 7.23
3. 3.92
4. 10.36

Ans: b

16.A metal ball weight 9 kN in air and 7.5 kN in a fluid of specific gravity 0.75,then specific gravity of ball material is

1. 7
2. 6
3. 4.5
4. 8

Ans: c

17.In a straight uniform pipe,the discharge is reduced from 1001 p.s. to zero in 10 seconds.The cross section area of the pipe is 200 Sq.cm.The nature and value of acceleration is

1. Tangential and 0.5m/s2
2. Normal and 0.5m/s2
3. Tangential and -0.5m/s2
4. Normal and -0.5m/s2

Ans: c

18.Pick out the dimensionless parameter

3. Energy per unit weight per second
4. Unit speed of a hydraulic turbine

Ans: a

19.A Pitot-tube measures

2. Velocity at stagnation point

Ans: c

20.All the terms of Bernoulli’s equation:(ρ/r)+(V2/2g)+Z =Constant have the units of

1. Joules per kilogram
2. Joules per Newton
3. Watt per Newton
4. Joules per Cubic meter

Ans: c