**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.)

- Equal to 3γ
- less than 3γ
- 3γ times depth of center of pressure
- Equal to 2γ

**Ans: a**

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

- hL ,Re
- f,Q
- hL ,Q
- a,L/D

**Ans: c**

**3.The pressure at the throat of Venturimeter is**

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

**Ans: b**

**4.Surface tension of a fluid is zero**

- When the fluid is at rest
- Inversely proportional to fluid mass density
- The result of interaction between
- Depend on the forces of molecular attraction

**Ans: d**

**5.A fluid is said to be the irrotational when**

- Fluid has zero vorticity.
- Flow is both steady and uniform
- Fluid obeys Newton’s law of viscosity
- 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**

- At rest
- Ideal and is in motion
- Frictionless
- 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**

- 10
- 1
- 1000
- 100

**Ans: c**

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

- Force per unit mass
- Work for unit acceleration
- Work per Unit Weight
- 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**

- 2 Kw
- 4 Kw
- 12 Kw
- 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**

- 4.71 cm
- 2.828 cm
- 4.414 cm
- 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**

- 69
- 103.5
- 34.5
- 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**

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

- 101
- 60
- 210
- 202

**Ans: d**

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

- a Torque
- A change in pressure
- A change in kinetic energy of Jet
- 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**

- 14.46
- 7.23
- 3.92
- 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**

- 7
- 6
- 4.5
- 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**

- Tangential and 0.5m/s2
- Normal and 0.5m/s2
- Tangential and -0.5m/s2
- Normal and -0.5m/s2

**Ans: c**

**18.Pick out the dimensionless parameter**

- Slope of hydraulic gradient
- Velocity gradient
- Energy per unit weight per second
- Unit speed of a hydraulic turbine

**Ans: a**

**19.A Pitot-tube measures**

- Dynamic head
- Velocity at stagnation point
- Total head
- Difference between total head and dynamic head

**Ans: c**

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

- Joules per kilogram
- Joules per Newton
- Watt per Newton
- Joules per Cubic meter

**Ans: c**

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