Fluid Mechanics (Part-4) (General Engineering) (SSC JE)

Total Questions: 41

11. Compressibility of air is [RRB JE (Ranchi) 04.01.2015 ]

Correct Answer: (a) Greater than that of water
Solution:

Compressibility–The property by virtue of which fluids undergo a change in volume under the action of external pressure is known as compressibility. • It decreases with the increase in pressure of fluid as the volume modulus increase with the increase of pressure.
Compressibility of air = 7.65 × 10⁻¹⁰Pa⁻¹
Compressibility of water = 5.1 × 10⁻¹⁰Pa⁻¹⁰

12. Centrifugal pump is an example of [RRB JE (Ranchi) 04.01.2015 ]

Correct Answer: (c) Steady flow system
Solution:

Centrifugal pump is a machine, which converts mechanical energy into pressure energy. The pump raises water from a lower level to a higher level by the action of centrifugal force.
• Centrifugal pump is an example of steady flow system.

13. In a tank or channel, notch is provided to measure [RRB JE (Ranchi) 04.01.2015 ]

Correct Answer: (c) Discharge
Solution:

Notch–A device used for measuring the rate of flow (discharge) of liquid through small opening is termed as notch.
Discharge through rectangular notch–

14. The shearing force per unit area required to maintain a unit difference in velocity between two parallel layers of a fluid at a unit distance apart is called? [RRB JE (Ranchi) 04.01.2015 ]

Correct Answer: (c) Co-efficient of absolute viscosity
Solution:

Coefficient of absolute viscosity is a measure of internal resistance, absolute viscosity is the tangential force per unit area required to move on horizontal plane with respect to another plane at an unit velocity, when maintaining an unit distance apart in the fluid.

15. When a particle is suspended in water, two forces are acting on it, which are [RRB S.S.E. 03.09.2015 (Shift-III) ]

Correct Answer: (b) Gravity and buoyant force
Solution:

When a particle is suspended in water, there are two forces acting on it which are gravity and buoyant force. Gravity acts in downward direction and buoyant force in upward direction. When these two forces are equal than particle start floating on the surface of liquid.
The magnitude of buoyant force depends upon the volume of an object immersed in liquid and the density of liquid.

16. Flow in a pipe is laminar, if the Reynold's number is: [RRB JE(Patna/Muzaffarpur/Chennai/Ahmedabad/Bangalore) 14.12.2014 ]

Correct Answer: (a) Less than 2000
Solution:

17. Centre of buoyancy always: [RRB JE(Patna/Muzaffarpur/Chennai/Ahmedabad/Bangalore) 14.12.2014 ]

Correct Answer: (b) Coincides with the centroid of the volume of the fluid displaced
Solution:

18. The velocity at which the flow changes from laminar to turbulent for the case of a given liquid at a given temperature and in a given pipe, is known as: [RRB JE (Muzaffarpur) 14.12.2014 ]

Correct Answer: (b) Critical velocity
Solution:

Critical velocity– The limiting value in which the flow streamlined and above which the velocity becomes turbulent is known as the critical velocity.
• The speed and direction in which the flow of a liquid changes from laminar to turbulent is known as the critical velocity of the fluid.

19. A flow, which the resistance to shearing deformation is zero : [RRB JE (Muzaffarpur) 14.12.2014 ]

Correct Answer: (d) Ideal flow
Solution:

Ideal flow–A flow is said to be ideal if the resistance to shearing deformation is zero because of no-viscosity between fluid layers takes place. Ideal flow is also known as inviscid flow.

20. In a steady flow process, the value of: [RRB JE (Muzaffarpur) 14.12.2014 ]

Correct Answer: (d) All of these
Solution:

Steady flow–The flow in which fluid properties does not change with time is termed as steady flow or stationary flow. In steady flow process the value of heat transfer, work transfer and mass flow at inlet and outlets is same in control volume.