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Multiple choice question for engineering

Set 1

1. A notch is a device used to measure the turbulence of the flowing liquid directly.
a) True
b) False

View Answer

Answer: b [Reason:] A notch is a device used to measure the flow rate of the flowing liquid, directly.

2. The weir is an attachable structure made up of thermoplastic.
a) True
b) False

View Answer

Answer: b [Reason:] The weir is a permanent masonry structure made up of concrete.

3. The notch is bigger in size than wier.
a) True
b) False

View Answer

Answer: b [Reason:] The weir is bigger in size than notch.

4. The MoM (Material of Manufacture) of notch is,
a) Thermoplastic
b) Metals
c) Fibre
d) Wood

View Answer

Answer: b [Reason:] The MoM (Material of Manufacture) of notch is Metals.

5. Which of the following is not a way of classifying notches or weirs?
a) Based on the shape of opening
b) Based on the effect of the sides on the nappe
c) Based on the shape of the crest
d) Based on the effect of the sides on the crest

View Answer

Answer: d [Reason:] There is no such way of classification.

6. The nature of discharge is also a way of classifying notches.
a) True
b) False

View Answer

Answer: b [Reason:] The nature of discharge is also a way of classifying notches.

7. Which of the following is not a way of classifying based on the shape of opening?
a) Rectangular notch
b) Circular notch
c) Trapezoidal notch
d) Stepped notch

View Answer

Answer: b [Reason:] Circular notch is not a way of classifying based on the shape of opening.

8. Trapezoidal weir has another popular name. What is it?
a) Cipolletti weir
b) Hagen Poiseuille’s weir
c) Reynold’s weir
d) Euler’s weir

View Answer

Answer: a [Reason:] Trapezoidal weir is also called Cipolletti weir.

9. What is not the way of classifying weir based on their shape of crest?
a) Sharp crested weir
b) Broad crested weir
c) Narrow crested weir
d) Trapezoidal crested weir

View Answer

Answer: d [Reason:] Trapezoidal crested weir is not the way of classifying weir based on their shape of crest.

10. What is not the way of classifying weir based on the emerging nappe?
a) Weir with end contraction
b) Weir without end contraction
c) Weir contraction at the beginning
d) Weir with absence of end contraction

View Answer

Answer: c [Reason:] This is not the way of classifying weir based on the emerging nappe.

Set 2

1. Which one of the following is the correct relation between compressibility β and Bulk Modulus k
a) β = k
b) β = 1/k
c) β = 2k
d) β = k/2

View Answer

Answer: b [Reason:] Compressibility β of a liquid is deβned as the ratio of volumetric strain to the compressive stress while Bulk Modulus is the ratio of compressive stress to volumetric strain. Hence, β = 1/k is the correct relation.

2. Which one of the following is true about Bulk Modulus of elasticity?
a) it is the ratio of compressive stress to volumetric strain
b) it is the ratio of compressive stress to linear strain
c) it is the ratio of tensile stress to volumetric strain
d) it is the ratio of tensile stress to linear strain

View Answer

Answer: a [Reason:] Bulk Modulus k is related to the compression of a liquid and the decrease in volume per unit volume. It is the ratio of compressive stress to the volumetric strain.

3. The value of the Bulk Modulus of elasticity for an incompressible fluid is
a) zero
b) unity
c) infinity
d) very low

View Answer

Answer: c [Reason:] k = 1/β, where k= Bulk Modulus of elasticity and β= compressibility. For an incompressible fluid, β=0, thus the value of k will tend to infinity.

4. Three fluids 1, 2 and 3 have Bulk Moduli of k1, k2 and k3 respectively. If k1 > k2 > k3, which liquid will have the highest compressibility?
a) liquid 1
b) liquid 2
c) liquid 3
d) they’ll have equal compressibilities

View Answer

Answer: c [Reason:] k = 1=β, where k= Bulk Modulus of elasticity and β= compressibility. If k1 > k2 > k3, then β1 < β2 < β3. Thus, liquid 3 will have the highest compressibility.

5. Bulk Modulus, Pressure, Force, Stress – Which one of these won’t have the same unit as the others?
a) Bulk Modulus
b) Pressure
c) Force
d) Stress

View Answer

Answer: c [Reason:] The SI unit of Bulk Modulus, Pressure and Stress is N/m2 but the unit of Force is N.

6. Which of the following is the dimension of Bulk Modulus?
a) [M1L-1T-1].
b) [M1L-1T-2].
c) [M1L1T-2].
d) [M1L1T-1].

View Answer

Answer: b [Reason:]

7. Which one of the following is the unit of compressibility?
a) m=N
b) m2=N
c) m3=N
d) it is unitless

View Answer

Answer: b [Reason:] k = 1/β, where k= Bulk Modulus of elasticity and β= compressibility. Thus the unit of Bulk modulus is N/m2 and the unit of compressibility becomes m2/N.

8. Which of the following is the dimension of compressibility?
a) [M1L1T-2].
b) [M1L1T-1].
c) [M-1L1T-2].
d) [M-1L1T2].

View Answer

Answer: d [Reason:] k = 1/β, where k = Bulk Modulus of elasticity and β= compressibility.

and [β] = [1/k] = [M-1L1T2].

Set 3

1. If a liquid enters a pipe of diameter d with a velocity v, what will it’s velocity at the exit if the diameter reduces to 0.5d?
a) v
b) 0.5v
c) 2v
d) 4v

View Answer

Answer: d [Reason:] According to the Continuity Equation, where a represents flow area, v represents flow velocity, i is for inlet conditions and o is for outlet conditions. fluid-mechanics-questions-answers-continuity-equation-q1a

2. The continuity equation is based on the principle of
a) conservation of mass
b) conservation of momentum
c) conservation of energy
d) conservation of force

View Answer

Answer: a [Reason:] According to the Continuity Equation, if no fluid is added or removed from the pipe in any length then the mass passing across different sections shall be the same. This is in accordance with the principle of conservation of mass which states that matter can neither be created nor be destroyed.

3. Two pipes of diameters d1 and d2 converge to form a pipe of diameter d. If the liquid flows with a velocity of v1 and v2 in the two pipes, what will be the flow velocity in the third pipe?
fluid-mechanics-questions-answers-continuity-equation-q3

View Answer

Answer: d [Reason:] According to the Continuity Equation, where a represents flow area, v represents flow velocity, i is for inlet conditions and o is for outlet conditions. Thus, fluid-mechanics-questions-answers-continuity-equation-q2a

4. Two pipes of diameters d1 and d2 converge to form a pipe of diameter 2d. If the liquid flows with a velocity of v1 and v2 in the two pipes, what will be the flow velocity in the third pipe?
a) v1 + v2
b) v1 + v2/2
c) v1 + v2/4
d) 2(v1 + v2)

View Answer

Answer: c [Reason:] According to the Continuity Equation, where a represents flow area, v represents flow velocity, i is for inlet conditions and o is for outlet conditions. Thus, fluid-mechanics-questions-answers-continuity-equation-q4a

5. Two pipes, each of diameter d, converge to form a pipe of diameter D. What should be the relation between d and D such that the flow velocity in the third pipe becomes double of that in each of the two pipes?
a) D = d
b) D = 2d
c) D = 3d
d) D = 4d

View Answer

Answer: a [Reason:] According to the Continuity Equation, fluid-mechanics-questions-answers-continuity-equation-q5 where a represents flow area, v represents flow velocity, i is for inlet conditions and o is for outlet conditions. Thus, A1v1 + A2v2 = Av d2v + d2v = D2v D = d.

6. Two pipes, each of diameter d, converge to form a pipe of diameter D. What should be the
relation between d and D such that the
ow velocity in the third pipe becomes half of that in each
of the two pipes?
a) D = d/2
b) D = d/3
c) D = d/4
d) D = d/5

View Answer

Answer: a [Reason:] According to the Continuity Equation, fluid-mechanics-questions-answers-continuity-equation-q5 where a represents flow area, v represents flow velocity, i is for inlet conditions and o is for outlet conditions. Thus, A1v1 + A2v2 = Av d2v + d2v = Dv/2 d = D ⁄ 4.

7. In a two dimensional flow, the component of the velocity along the X-axis is u = ax2 + bxy + cy2.
If v = 0 at y = 0, what will be the velocity component in the Y-direction?
a) v = 2axy + by2
b) v = 2axy + b ⁄ 2 y2
c) v = -2axy – b ⁄ 2 y2
d) v = -axy – b ⁄ 2 y2

View Answer

Answer: c [Reason:] According to the condition for continuity, fluid-mechanics-questions-answers-continuity-equation-q7

8. In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ax2 + bxy + cy2 and v = cxy. What should be the condition for the flow field to be continuous?
a) a + c = 0
b) b + c = 0
c) 2a + c = 0
d) 2b + c = 0

View Answer

Answer: c [Reason:] According to the condition for continuity, 2ax + cx = 0 2a + c = 0.

9. In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = axy and v = bx2 + cy2. What should be the condition for the flow field to be continuous?
a) a + b = 0
b) a + c = 0
c) a + 2b = 0
d) a + 2c = 0

View Answer

Answer: d [Reason:] The condition for the flow field to be continuous is: ay + 2cy = 0 a + 2c = 0.

10. In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ax2 + bxy and v = cxy +dy2. What should be the condition for the flow field to be continuous?
a) (a + b)x + (c + d)y = 0
b) (a + c)x + (b + d)y = 0
c) (2a + b)x + (c + 2d)y = 0
d) (2a + c)x + (b + 2d)y = 0

View Answer

Answer: d [Reason:] The condition for the flow field to be continuous is: 2ax + cx + by + 2dy = 0 (2a + c)x + (b + 2d)y = 0.

11. In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ax2 + bxy and v = bxy + ay2. The condition for the flow field to be continuous is
a) independent of the constants (a; b) but dependent on the variables (x; y)
b) independent of the variables (x; y) but dependent on the constants (a; b)
c) independent of both the constants (a; b) and the variables (x; y)
d) dependent on both the constants (a; b) and the variables (x; y)

View Answer

Answer: a [Reason:] The condition for the flow field to be continuous is: 2ax + by + 2ay + bx = 0 x + y = 0 Hence, the condition for the flow field to be continuous is independent of the constants (a; b) and dependent only on the variables (x; y).

12. In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ax + by and v = ax – by. For what condition will the flow field be continuous?
a) impossible
b) possible if a = b
c) possible if a = 2b
d) possible for all values of a and b

View Answer

Answer: d [Reason:] The condition for the flow field to be continuous is: fluid-mechanics-questions-answers-continuity-equation-q12 Thus, the condition will be satisfied for any and every value of a and b.

13. In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ay2 + bxy and v = ax2 + bxy. The flow will be continuous if
a) a + b = 0
b) a – b = 0
c) x + y = 0
d) x – y = 0

View Answer

Answer: c [Reason:] The condition for the flow field to be continuous is: by + bx = 0 x + y = 0.

14. In a two dimensional flow, the component of the velocity along the X-axis and the Y-axis are u = ax2 + bxy and v = bxy + ay2. The condition for the flow field to be continuous is
a) independent of a and b
b) independent of a and c
c) independent of b and c
d) independent of a, b and c

View Answer

Answer: d [Reason:] The condition for the flow field to be continuous is: 2ax + by + 2ay + bx = 0 x + y = 0 Hence, the condition for the flow field to be continuous is independent of a, b and c.

15. In a water supply system, water flows in from pipes 1 and 2 and goes out from pipes 3 and 4 as shown. If all the pipes have the same diameter, which of the following must be correct?
fluid-mechanics-questions-answers-continuity-equation-q15
a) the sum of the flow velocities in 1 and 2 is equal to that in 3 and 4
b) the sum of the flow velocities in 1 and 3 is equal to that in 2 and 4
c) the sum of the flow velocities in 1 and 4 is equal to that in 2 and 3
d) the flow velocities in 1 and 2 is equal to that in 3 and 4

View Answer

Answer: a [Reason:] According to the Continuity Equation, where a represents flow area, v represents flow velocity, i is for inlet conditions and o is for outlet conditions. A1v1 + A2v2 = A3v3 + A4v4 Since d1 = d2 = d3 = d4, v1 + v2 = v3 + v4.

Set 4

1. The continuity equation is based on the premise of-
a) Law of conservation of energy
b) Law of conservation of mass
c) Law of conservation of momentum
d) None of the mentioned

View Answer

Answer : b [Reason:] Continuity equation is based on the the principle of conservation of mass.

2. The continuity equation is only applicable to incompressible fluid.
a) True
b) False

View Answer

Answer : b [Reason:] The continuity equation is only applicable to incompressible as well as compressible fluid.

3. For incompressible fluid flow, if area reduces then what is the effect on the velocity.
a) increases
b) decreases
c) first increases then decreases
d) first decreases then increases

View Answer

Answer : a [Reason:] According to continuity equation, Area × velocity = constant Hence, as area decreases velocity increases.

4. For compressible fluid flow in a pipe, having decrease in specific gravity what will be the effect of decrease in diameter?
a) It will cause increase in velocity
b) It will cause decrease in velocity
c) It remains constant
d) None of the mentioned

View Answer

Answer: a [Reason:] According to continuity equation, ρ*A*v = constant Hence, as density and area decreases velocity is bound to increase.

5. What is the most common assumption while dealing with fluid flow problems using continuity equation?
a) Flow is assumed to be compressible
b) Flow is assumed to be unsteady
c) Flow is assumed to be steady
d) Flow is assumed to be turbulent

View Answer

Answer: c [Reason:] In majority of the fluid flow problems, flow is assumed to be steady.

6. The diameters of a pipe at the sections 1 and 2 are 8 cm and 13 cm respectively. Find the discharge through pipe if the velocity of water flowing through the pipe at section 1 is 6 m/s. Determine also the velocity at section 2.
a) 2.27 m/s
b) 4.54 m/s
c) 1.13 m/s
d) 3.25 m/s

View Answer

Answer : a [Reason:] According to continuity equation, Area × velocity = constant Area1*Velocity1 = Area2*Velocity2 Velocity2=(Area1*Velocity1)/Area2 = (82 * 6) / 132=2.27 m/s.

7. The continuity equation can only be used for analysis of conserved quantity.
a) True
b) False

View Answer

Answer: a [Reason:] Continuity equation is defined on a control volume and hence, is applicable only to Conserved quantities.

8. The diameter of a pipe at the section 1 is 9 cm. If the velocity of water flowing through the pipe at section 1 is 4.8 m/s and section 2 is 9 m/s, Determine the area at section 2.
a) 33.93 m2
b) 67.86 m2
c) 16.96 m2
d) 38.66 m2

View Answer

Answer : a [Reason:] According to continuity equation, Area × velocity = constant Area1*Velocity1 = Area2*Velocity2 (Area1*Velocity1)/Velocity2=Area2 Area 2= 33.93 m2.

9. For a flow to be physically possible it must primarily satisfy which equation?
a) Equation of conservation of energy
b) Equation of conservation of mass or continuity equation
c) Equation of conservation of momentum
d) None of the mentioned

View Answer

Answer: a [Reason:] Fluid flow must satisfy equation of conservation of mass or continuity equation, for itto be physically possible.

10. Continuity equation can also be derived for polar coordinate system
a) True
b) False

View Answer

Answer: a [Reason:] Continuity equation in polar coordinate is also used for analysis.

Set 5

1. When is orifice called ‘large orifice’?
a) If the head of liquid is less than 5 times the depth of orifice
b) If the head of liquid is less than 2.5 times the depth of orifice
c) If the head of liquid is less Hence, 4 times the depth of orifice
d) If the head of liquid is less than 1.5 times the depth of orifice

View Answer

Answer: a [Reason:] It is the correct parametric definition for ‘large orifice’.

2. In case of any orifice, velocity always remains constant and hence discharge can be calculated.
a) True
b) False

View Answer

Answer: b [Reason:] In case of large orifice, velocity always remains variable and hence discharge cannot be calculated.

3. Find the discharge through a rectangular orifice 2.2 m wide and 1.3 m deep fitted to a easier tank. The water level in a team is 2.5 m above the top edge of orifice.
a) 13.9 m3/s
b) 11.5 m3/s
c) 16.9 m3/s
d) 8.7 m3/s

View Answer

Answer: a [Reason:] Q = 2/3 Cd *b*√2g* (H21.5 – H11.5) Here, H1 = 3.8 H2 = 2.5 b = 2.2 Hence, Q = 13.9 m3/s.

4. Find the discharge through a rectangular orifice 3.2 m wide and 1.7 m deep fitted to a easier tank. The water level in a team is 3.3 m above the top edge of orifice. Take Cd = 0.6
a) 29.4 m3/s
b) 58.5 m3/s
c) 67.9 m3/s
d) 78.7 m3/s

View Answer

Answer: a [Reason:] Q = 2/3 Cd *b*√2g* (H21.5 – H11.5) Here, H1 = 5 H2 = 3.3 b = 3.2 Hence, Q = 29.4 m3/s.

5. Find the discharge through totally drowned orifice of width 2.3 m if the difference of water levels on both side of the orifice be 40 cm. The height of water from to and bottom of the orifice are 2.6 m and 2.75 m respectively.
a) .56 m3/s
b) .64 m3/s
c) .75 m3/s
d) .55 m3/s

View Answer

Answer: a [Reason:] Q = Cd * b * (H2 – H1) √2gH Here, b = 2.3 H2 = 2.75 H1 = 2.6 H = 40 Q = .56 m3/s.

6. Find the discharge through totally drowned orifice of width 3.3 m if the difference of water levels on both side of the orifice be 50 cm. The height of water from to and bottom of the orifice are 2.25 m and 2.67 m respectively.
a) 2.8 m3/s
b) 2.7 m3/s
c) 2.6 m3/s
d) 2.5 m3/s

View Answer

Answer: a [Reason:] Q = Cd * b * (H2 – H1) √2gH Here, b = 3.3 H2 = 2.67 H1 = 2.25 H = 50 Q = 2.6 m3/s.

7. A rectangular orifice of 2 m width and 1.2 m deep is fitted in one side of large tank. The easier level on one side of the orifice is 3m above the top edge of the orifice while on the other side of the orifice the water level is 0.5 m below it’s top edge. Calculate discharge if Cd = .64
a) 4.95 m3/s
b) 5.67 m3/s
c) 3.56 m3/s
d) 6.75 m3/s

View Answer

Answer: a [Reason:] Explanation: Q = Cd * b * (H2 – H) √2gH Here, b = 2 H2 = 4.2

H = 3.5 Q = 4.94 m3/s.

8. The time taken to empty the tank is independent of Cd but depends only on the height and acceleration due to gravity.
a) True
b) False

View Answer

Answer: b [Reason:] The time taken to empty the tank is dependent on Cd as well as depends only on the height and acceleration due to gravity.

9. The discharge rate is independent of the height difference and dependent only on the height.
a) True
b) False

View Answer

Answer: b [Reason:] The discharge rate is dependent of the height difference and dependent only on the height.

10. In case of submerged orifice the discharge is substantially dependent on temperature of fluid
a) True
b) False

View Answer

Answer: b [Reason:] Discharge is dependent on temperature but minimally.