Fluid Mechanics (General Engineering) (SSC JE)

Total Questions: 50

21. A fluid flow in which velocity, pressure, density, temperature etc., which describe the behaviour of the fluid in motion, do not change with time, is said to be: [JSSC JE (GEN. ENGG.)- 03.11.2022 ]

Correct Answer: (d) Steady flow
Solution:

Steady flow–A fluid flow in which velocity, pressure, density, temperature etc. do not change with time is said to be steady flow.

Unsteady flow–A fluid flow in which velocity, pressure, density, temperature etc. change with time is said to be unsteady flow.

Uniform flow–A flow in which the liquid particles at all sections of a pipe or channel have the same velocities is called uniform flow.

Laminar and turbulent flow–In laminar flow, the particles moves in layer sliding smoothly over the adjacent layer while in turbulent flow particles have the random and erratic movement, intermixing in the adjacent layer.

22. Identify the most appropriate reason for application of Bernoulli equation. It can not be applied if the flow is: [JSSC JE (GEN. ENGG.)- 03.11.2022 ]

Correct Answer: (d) rotational, turbulent and unsteady
Solution:

Application of Bernoulli equation–For the Bernoulli equation to be applicable all the flows are steady, incompressible, frictionless, irrotational and along the same stream line.

23. Fluid cannot resist: [JSSC JE (GEN. ENGG.)- 03.11.2022 ]

Correct Answer: (d) shear stress
Solution:

Viscosity–A fluid at rest cannot resist any shearing force, but once the fluid in motion, shearing forces are then set up between layers of the fluid which them moving at different velocities.

• The viscosity of a fluid is a measure of the ability of the fluid to resist these shearing forces.

24. Primarily, a Piezometer is used to measure: [JSSC JE (GEN. ENGG.)- 03.11.2022 ]

Correct Answer: (a) very low pressure
Solution:

Piezometer–It is the simplest form of manometer used for measuring gauge pressure or low pressure. One end of this manometer is connected to the point where pressure is to be measured and other end is open to the atmosphere.

25. Match the columns. [JSSC JE (GEN. ENGG.)- 03.11.2022 ]

Correct Answer: (b) A-2, B-3, C-1, D-4
Solution:

26. What does "Hydraulic Gradient Line" (HGL) represent in fluid flow? [JSSC JE (GEN. ENGG)-2017 ]

Correct Answer: (a) Piezometric head available to a fluid during the flow
Solution:

27. During fluid flow in a pipe, a venturimeter is used to measure the flow rate. The pipe should be: [JSSC JE (GEN. ENGG.)- 03.11.2022 ]

Correct Answer: (a) in any position
Solution:

During fluid flow in a pipe, a venturimeter is used to measure the flow rate. The pipe should be in any position.
Venturimeter–It is an instrument used to measure the discharge of liquid flowing in a pipe. It consists of three part–
1. Converging zone
2. Throat
3. Diverging zone.

28. Which of the following is the expression for mass density of a substance? [JSSC JE (GEN. ENGG)-2017 ]

Correct Answer: (b) Mass/volume
Solution:
Density–It is the ratio of mass to the volume of fluid.

29. What is the specific weight of water in SI units? [JSSC JE (GEN. ENGG)-2017 ]

Correct Answer: (c) 9.81 kN/m³
Solution:

30. Straight converging streamlines denote: [JSSC JE (GEN. ENGG.)- 31.10.2022 ]

Correct Answer: (a) convective tangential acceleration
Solution:

Stream line
 It is the line drawn in the flow such that tangent to it any point is the direction of velocity at that point. Stream line is a set of concentric circle with origin at center.
• Spacing between stream line varies inversely as the velocity of flow.
• Straight converging stream lines denote convective tangential acceleration.

Streak line–Locus of all fluid particle at an instant which crossed some fixed point in the flow space.
• Streak line is formed by continuous introduction of dye or smoke from a point in the flow.
• For steady flow, path line and stream line are same.