# Food Engineering Questions and Answers – Unit Operations – Fluid Mechanics-1

This set of Food Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Unit Operations – Fluid Mechanics-1”.

1. Statement 1: Bernoulli’s equation can be applied to flow through pipes both, with and without friction.
Statement 2: Air is an incompressible fluid.
a) True, False
b) True, True
c) False, False
d) False, True

Explanation: Bernoulli’s equation can be applied to flow through pipes both, with and without friction. Gases and vapours are compressible fluids. Hence air is compressible.

2. What is Kinetic Energy Factor in the Bernoulli’s equation?
a) It is because friction varies
b) It is because friction stays constant
c) It is because the velocity in every layer varies and only the average velocity is accounted hence a correction factor is a need
d) None of the mentioned

Explanation: Kinetic Energy Factor in the Bernoulli’s equation is because the velocity in every layer varies and only the average velocity is accounted hence a correction factor is a need.

3. In Bernoulli’s equation, the friction correction factor is added to the LHS and the energy contributed by the pump is written on the RHS.
a) True
b) False

Explanation: In the Bernoulli’s equation, the friction correction factor is added to the RHS and the energy contributed by the pump is written on the LHS.

4. Statement 1: Reynolds number is the ratio of viscous force to Inertial Force.
Statement 2: The thickness of Boundary layer increases with the increase in distance from the surface.
a) True, False
b) True, True
c) False, False
d) False, True

Explanation: Reynolds number is the ratio of Inertial Force to viscous force. The thickness of the Boundary layer decreases with the increase in distance from the surface.

5. The energy loss due to the friction at the walls of a pipe is called _____
a) Kinetic friction
b) Skin friction
c) Static friction
d) None of the mentioned

Explanation: The energy loss due to the friction at the walls of a pipe is called Skin friction.

6. Statement 1: Friction factor ‘f’ is an important factor in turbulent flow.
Statement 2: ‘f’ is the ratio of shear stress (ϩw) to kinetic energy head ((ρv2)⁄2g).
a) True, False
b) True, True
c) False, False
d) False, True

Explanation: Both the statements are true.

7. Which of the following pumps is this pump- It has no rotating or reciprocating parts involved. No leakage. Air/gas used to impart energy.
a) Piston pump
b) Diaphragm pump
c) Gear pump
d) Air-lift pump

Explanation: Air-lift pump has no rotating or reciprocating parts involved. No leakage. Air/gas used to impart energy.

8. Statement 1: Non-Newtonian fluids have a linear relationship between shear stress and shear strain.
Statement 2: Tubes are larger than pipes in diameter and have thicker walls.
a) True, False
b) True, True
c) False, False
d) False, True

Explanation: Newtonian fluids have a linear relationship between shear stress and shear strain. Pipes are larger than tubes in diameter and have thicker walls.

9. Pipes are described in the form of _____
a) None of the mentioned
b) Formation Number
c) All of the mentioned
d) Schedule Number

Explanation: Pipes are described in the form of Schedule Number.

10. Statement 1: Two pipes are joined using _____
Statement 2: The sealing material between two pipes to be joined is called _____
a) Union Joint, Coupling

Explanation: Two pipes are joined using Coupling. The sealing material between two pipes to be joined is called Gasket.

11. Statement 1: When an additional connection such as a valve/ tap is to be added, _____ is used.
Statement 2: Bents have more pressure drop than elbows.
a) Union joint, True
b) Union joint, False
c) T- joint, True
d) T- joint, False

Explanation: When an additional connection such as a valve/ tap is to be added, T- joint is used. Bents and elbows are both used when there is a change in the direction of flow. But, pressure drop in bents is more than in elbows, although bents are sturdier than elbows.

12. Which of the following is true about On-Off Control?
a) On-Off valves are called Plug Cocks
b) The size of the valve path is as big as the pipe itself
c) Pressure drop in these is the least compared to all other valves
d) All of the mentioned

Explanation: All the given statements are true.

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