Test 14 - Darcy-Weisbach Equation and Major Pipe Losses

Question 1 ప్రశ్న 1

In pipe-flow terminology, what is meant by the major head loss?

A Distributed loss caused primarily by wall friction over the length of a pipe B Loss occurring only at a sudden enlargement C Loss produced only by an entrance or exit D Loss caused exclusively by a change in elevation

Question 2 ప్రశ్న 2

Unless otherwise stated, let f denote the Darcy friction factor. Which equation gives the major head loss in a circular pipe?

A hf = f(D/L)(V²/2g) B hf = f(L/D)(V²/2g) C hf = 4f(D/L)(V²/2g) D hf = f(L/D)(2g/V²)

Question 3 ప్రశ్న 3

Which statement about the quantities in the Darcy-Weisbach equation hf = f(L/D)(V²/2g) is correct?

A Both f and L/D are dimensionless B The friction factor f has dimensions of length C V²/(2g) has dimensions of velocity D The diameter D must have dimensions of area

Question 4 ప్రశ్న 4

A uniform pipe experiences a frictional head loss of 6.0 m over a length of 300 m. What is the friction slope Sf = hf/L?

A 0.002 B 0.010 C 0.020 D 0.050

Question 5 ప్రశ్న 5

Water flows at a mean velocity of 2.0 m/s through a 200 mm diameter pipe 100 m long. If the Darcy friction factor is 0.020, what is the major head loss? Take g = 9.81 m/s².

A 1.02 m B 2.04 m C 4.08 m D 8.15 m

Question 6 ప్రశ్న 6

For the horizontal constant-diameter water pipe in the previous type of calculation, suppose the frictional head loss is 2.0387 m. If ρ = 1000 kg/m³ and the mean velocities at the two sections are equal, what frictional pressure drop corresponds to this loss?

A 10.0 kPa B 20.0 kPa C 40.0 kPa D 80.0 kPa

Question 7 ప్రశ్న 7

A pipe 60 m long and 150 mm in diameter carries fluid at a mean velocity of 2.5 m/s. If the measured major head loss is 3.0 m, what is the Darcy friction factor? Take g = 9.81 m/s².

A 0.0118 B 0.0235 C 0.0471 D 0.0942

Question 8 ప్రశ్న 8

A pipe has diameter 120 mm and Darcy friction factor 0.024. Fluid flows through it at 2.2 m/s and experiences a major head loss of 4.0 m. What pipe length produces this loss? Take g = 9.81 m/s².

A 40.5 m B 60.8 m C 81.1 m D 162.1 m

Question 9 ప్రశ్న 9

A pipe 100 m long carries fluid at 3.0 m/s. If the Darcy friction factor is specified as 0.020 and the permitted major head loss is 5.0 m, what pipe diameter is required when f is treated as constant for this calculation? Take g = 9.81 m/s².

A 91.7 mm B 137.6 mm C 183.5 mm D 275.2 mm

Question 10 ప్రశ్న 10

Fluid flows through a 250 mm diameter pipe 150 m long. If the Darcy friction factor is 0.025 and the major head loss is 6.0 m, what is the mean velocity? Take g = 9.81 m/s².

A 1.40 m/s B 2.00 m/s C 2.80 m/s D 5.60 m/s

Question 11 ప్రశ్న 11

Water flows through an 80 m long, 200 mm diameter pipe. If the Darcy friction factor is 0.020 and the allowed major head loss is 4.0 m, what discharge can the pipe carry? Take g = 9.81 m/s².

A 0.0492 m³/s B 0.0984 m³/s C 0.1968 m³/s D 0.3936 m³/s

Question 12 ప్రశ్న 12

A pipe must carry Q = 0.050 m³/s over a length of 200 m with a maximum major head loss of 10 m. If the Darcy friction factor may be treated as constant at 0.020, what theoretical pipe diameter is required? Take g = 9.81 m/s².

A 101.7 mm B 127.1 mm C 152.6 mm D 203.4 mm

Question 13 ప్రశ్న 13

If Darcy friction factor, pipe length and mean velocity are held constant, how does major head loss vary with pipe diameter?

A hf is proportional to D B hf is proportional to D² C hf is proportional to 1/D D hf is proportional to 1/D²

Question 14 ప్రశ్న 14

For a circular pipe carrying a fixed discharge Q, assume the Darcy friction factor and pipe length remain constant. How does the major head loss vary with diameter?

A hf is proportional to D^-1 B hf is proportional to D^-2 C hf is proportional to D^-4 D hf is proportional to D^-5

Question 15 ప్రశ్న 15

A uniform pipe is replaced by another pipe of twice the length but with the same diameter, Darcy friction factor and mean velocity. How does the major head loss change?

A It is halved B It remains unchanged C It doubles D It becomes four times as large

Question 16 ప్రశ్న 16

For a given pipe with constant Darcy friction factor, what happens to the major head loss if the mean velocity is doubled?

A It is halved B It doubles C It becomes four times as large D It becomes eight times as large

Question 17 ప్రశ్న 17

For a fixed circular pipe, assume the Darcy friction factor remains unchanged. If the discharge is doubled, what happens to the major head loss?

A It doubles B It becomes four times as large C It becomes eight times as large D It remains unchanged

Question 18 ప్రశ్న 18

Water flows at 0.030 m³/s through a pipe in which the major frictional head loss is 8.0 m. What hydraulic power is dissipated by pipe friction? Take ρ = 1000 kg/m³ and g = 9.81 m/s².

A 1.18 kW B 2.35 kW C 4.71 kW D 7.85 kW

Question 19 ప్రశ్న 19

A liquid flow of 0.025 m³/s experiences a frictional pressure drop of 120 kPa through a pipe section. What rate of mechanical-energy loss is associated with this pressure drop when elevation and mean velocity are unchanged between the ends?

A 1.50 kW B 3.00 kW C 4.80 kW D 6.00 kW

Question 20 ప్రశ్న 20

In a fixed pipe, assume the Darcy friction factor remains unchanged. If the discharge increases by 20%, by what factor does the major head loss change?

A 1.20 B 1.40 C 1.44 D 2.00

Question 21 ప్రశ్న 21

Water flows at 0.120 m³/s through a 300 mm diameter pipe 250 m long. If the Darcy friction factor is 0.018, what is the major head loss? Take g = 9.81 m/s².

A 1.10 m B 2.20 m C 4.41 m D 8.81 m

Question 22 ప్రశ్న 22

For a circular pipe with fixed Darcy friction factor, the major-loss relation may be written hf = RQ². For f = 0.020, L = 100 m and D = 0.20 m, what is R approximately when g = 9.81 m/s²?

A 129.1 s²/m⁵ B 258.2 s²/m⁵ C 516.4 s²/m⁵ D 1032.8 s²/m⁵

Question 23 ప్రశ్న 23

A calculation uses the Darcy-Weisbach form hf = f(L/D)(V²/2g). A source instead supplies a Fanning friction factor fF = 0.005. What value should be used for f in the stated Darcy-Weisbach equation?

A 0.00125 B 0.005 C 0.020 D 0.080

Question 24 ప్రశ్న 24

For steady flow through a uniform constant-diameter pipe with no pump or turbine and with only distributed pipe friction considered, which statement about the friction slope and energy grade line is correct?

A The magnitude of the energy-grade-line slope is hf/L B The energy grade line must rise in the direction of flow C Friction slope is V²/(2g) regardless of pipe length D The energy grade line is unaffected by wall friction

Question 25 ప్రశ్న 25

Consider the following statements about major pipe losses using the Darcy friction factor: I. For specified f, D and V, Darcy-Weisbach head loss is directly proportional to pipe length. II. For specified f, L and Q in a circular pipe, head loss is proportional to D^-5. III. Frictional hydraulic-power loss is ρgQhf. IV. A so-called minor loss can exceed the distributed major loss in a sufficiently short system. Which option is correct?

A I and II only B I, II and III only C II, III and IV only D I, II, III and IV

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