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# Fluid Mechanics MCQ – Pipes in Series

The liquid flowing through a series of pipes can take up__________

a) Pipes of different diameters

b) Pipes of the same diameters only.

c) Single pipe only

d) Short pipes only

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Answer: a

Explanation: When pipes of different diameters are connected at its ends to form a pipe, this pipe so developed is called as pipes in series. They might not have to be of the same diameters. But, having the same diameters are better as it avoids the losses so developed.

What is the total loss developed in a series of pipes?

a) Sum of losses in each pipe only

b) Sum of local losses only

c) Sum of local losses plus the losses in each pipe

d) Zero

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Answer: c

Explanation: When the pipes of different diameters are connected in series from end to end to form a pipe line. The total loss so developed is equal to the sum of local losses plus the losses in each pipe. The local losses are developed at the connection point.

The total head loss for the system is equal to_________

a) Pipe length

b) Pipe diameter

c) Width of the reservoir

d) Height difference of reservoirs

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Answer: d

Explanation: Total head loss for a system is equal to the height difference of the reservoirs. Height difference is denoted by the letter ‘H’. Total head loss can be equated by summing it up with all the local losses and the losses at each pipe.

Which among the following is not a loss that is developed in the pipe?

a) Entry

b) Exit

c) Connection between two pipes

d) Liquid velocity

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Answer: d

Explanation: Liquid velocity in the pipe is the velocity with which the liquid travels through different cross sections of the pipe. It is a vector field which is used to describe the motion of a continuum. The length of flow velocity vector is equal to the flow speed.

Which among the following is the correct formula for head loss?

a) Z1-Z2

b) C

c) T2-T1

d) S2-S1

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Answer: a

Explanation: Total head loss for a system is equal to the height difference of the reservoirs. Height difference is denoted by the letter ‘H’. Total head loss can be equated by summing it up with all the local losses and the losses at each pipe. Here, the height difference between the reservoirs is Z1-Z2.

If the two reservoirs are kept at the same level, the head loss is _______

a) Z1-Z2

b) Zero

c) T2-T1

d) S2-S1

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Answer: b

Explanation: Total head loss for a system is equal to the height difference of the reservoirs. Height difference is denoted by the letter ‘H’. The height difference between the reservoirs is Z1-Z2. Since they are of the same level, Z1=Z2. Therefore, head loss is zero.

How do we determine the total discharge through parallel pipes?

a) Add them.

b) Subtract them

c) Multiply them

d) Divide them

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Answer: a

Explanation: Total discharge in parallel pipes are determined by adding the discharges so developed in individual pipes. If Q1 is the discharge through pipe 1 and Q2 is the discharge through pipe 2. Then the total discharge through parallel pipes is equal to Q1+Q2.

The pipe diameter is ________

a) Directly proportional to fluid density

b) Directly proportional to mass flow rate

c) Inversely proportional to mass flow rate

d) Directly proportional to fluid velocity

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Answer: b

Explanation: The pipe diameter is directly proportional to mass flow rate of fluid. Pipe diameter can be calculated if volumetric flow rate and velocity are known. ‘D’ is inversely proportional to its velocity.

Define Viscosity.

a) Resistance to flow of object

b) Resistance to flow of air

c) Resistance to flow of fluid

d) Resistance to flow of heat

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Answer: c

Explanation: Viscosity is developed due to the relative motion between two surfaces of fluids at different velocities. It happens due to the shear stress developed on the surface of the fluid.

Coefficient of friction of a laminar flow is_________

a) Re/16

b) Re/64

c) 16/Re

d) 64/Re

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Answer: c

Explanation: Coefficient of friction is defined as the value that shows relationship between force and the normal reaction. It is mainly used to find out an object’s normal force and frictional force. Thus, it is equal to 16/Re.