## [MCQ’s]Fluid Mechanics-I

#### Module-1

1. Which of the following is not a method of control of mass movement?
a) Afforestation
b) Retaining wall
c) Chemical treatment of rocks
d) Deforestation
Explanation: The widely adopted methods for control of mass movements include, construction of retaining walls, chemical treatment of rocks, rock bolting and to some extent afforestation can avoid mass movements, but, deforestation promotes mass movements.

2. While devising a monitoring system, what has to be kept in mind?
a) Factor of safety
b) Cost-benefit ratio
c) Stress factor
d) Dip factor
Explanation: In devising a monitoring system, the cost-benefit ratio has to be kept in mind in all the cases because such systems are invariably expensive.

3. Which of the following might not reduce the chances of infiltration?
a) Cooling the slope material
b) Oiling the surface of slopes
c) Electro-osmosis of the slope material
d) Heating of the slope material
Explanation: Oiling of the slope surfaces, electro-osmosis and heating of the slope material have been also used in different countries to stabilize slopes by reducing chances of infiltration during heavy rains.

4. Retraining structures may prove exceptionally successful when?
a) The ground is too fine
b) The sliding mass is likely to remain wet
c) The movement is of deep nature
d) The sliding mass is likely to remain dry
Explanation: Retaining structures may prove exceptionally successful where- the ground is neither too fine nor too plastic; the sliding mass is likely to remain dry and the movement is of a shallow nature and limited extent.

5. When might the retaining walls prove to be not costly?
a) When the movement is of deep nature
b) When the movement is of unlimited nature
c) When the movement is shallow in nature
d) When the rocks are too heavy
Explanation: Retaining walls may prove costly failures when they are designed to resist slides of great volume and thickness or long rising slopes.

6. Pneumatically applied mortar or concrete is called __________
a) Grout
b) Gunite
c) Geo-polymer concrete
d) Geniter
Explanation: Gunite, is pneumatically applied mortar or concrete. The mixture of cement and sand (1:3) with little water is applied on the face under pressure and is known to develop sufficient strength on settling and hardening.

7. Which of the following is not a method of slope treatment?
a) Providing drainage systems
b) Flattening the slope
d) Digging rock traps
Explanation: Usually the slope treatment methods include, flattening the slope to ensure stable limits, decreasing the load and also digging rock traps in the form of ditches at the foot of a slope and providing benches at proper intervals. Providing a drainage system is a drainage method.

8. Which type of trees and plants are more effective in reducing infiltration?
a) Tropical
b) Deciduous
c) Temperate
d) Plantation
Explanation: Afforestation of potentially unstable slopes reduces the risk of their failure considerably. Vegetation cover, especially of deciduous trees and plants reduces the quantity of infiltration.

9. More often a combination of methods may have to be used for stabilising the slopes.
a) True
b) False
Explanation: While devising a slide-control program for an unstable area, it is always useful to weigh relative merits of methods available. More often, it may be a combination of methods rather than a single method that may have to be used for stabilising the slope.

10. Removal of water is done only by subsurface drainage.
a) True
b) False
Explanation: Drainage involves the removal of water from within the mass as well as preventing any further water reach the material susceptible to failure. This may be achieved either by surface drainage or by subsurface drainage or by both methods.

11. 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
Explanation: 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.

12. 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
Explanation: 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.

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

14. 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
Explanation: 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.

15. 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
Explanation: The SI unit of Bulk Modulus, Pressure and Stress is N/m2 but the unit of Force is N.

16. Which of the following contribute to the reason behind the origin of surface tension?
a) only cohesive forces
c) neither cohesive forces nor adhesive forces
d) both cohesive forces and adhesive forces
Explanation: The molecules on the surface of a liquid experience cohesive forces due to surrounding liquid molecules acting downward and adhesive forces due to surrounding gaseous molecules acting upwards. Surface tension orginates due to this unbalanced force on the surface molecules.

17. A liquid jet of 5 cm diameter has a pressure difference of N/m2. (Take surface tension as 0.075 N/m)
a) 12
b) 6
c) 3
d) 1.5
Explanation: p = σ/d
where p = pressure difference between the bubble and the surrounding medium, σ = surface tension and d = diameter of the bubble. Substituting all the values,
p = 0.075 / 5 * 10-2 = 1.5 N/m2.

18. The rise in the level of a liquid in a tube is h. If half the amount is poured outside, what will be the new rise in liquid level?
a) 0
b) h/2
c) h
d) 2h
Explanation: The rise in liquid level for a liquid is independent of the amount of liquid present in the tube. Since, same tube is used and same liquid is considered, the rise in the liquid level will remain the same.

19. A water drop of diameter 1 cm breaks into 1000 similar droplets of same diameter. What will be the gain or loss in the surface energy? (Take surface tension as 0.075 N/m)
a) gain of 0.424 mJ
b) gain of 0.212 mJ
c) loss of 0.212 mJ
d) loss of 0.424 mJ
Explanation: According to the Principle of Conservation of mass, M = 1000 * m, where M = mass of the big drop, m = mass of each droplet. Assuming density to be constant, D3 = 1000 * d3, i.e. D = 10d, where D = diameter of big drop, d = diameter of a droplet.
Change in surface energy = Surface tension * Change in surface area = 0:075*(1000 * πd2 – πD2) = 0:075 * (10 * πD2 – πD2) = 0:075 * 9π * (10-2)2 = 0:212 mJ Since, the change is positive, there will be a gain in the surface energy.

20. Calculate the magnitude of capillary effect in millimeters in a glass tube of 7mm diameter, when immersed in mercury. The temperature of the liquid is 25℃ and the values of surface tension of mercury at 25℃ is 0.51 N/m. The angle of contact for mercury is 130°.
a) 140
b) 280
c) 170
d) 210
Explanation: Capillarity rise or fall
h=4*cosθ*σ/ρ*g*d
=4*cos130*0.51/13600*9.81*0.007
=140 mm.

21. Determine the minimum size of glass tube that can be used to measure water level if the capillary rise in the tube is restricted to 5mm. Consider surface tension of water in contact with air as 0.073 N/m
a) 5.95mm
b) 11.9mm
c) 2.97mm
d) 4.46mm
Explanation: d=4*cosθ*σ/ρ*g*h
=4*1*0.073/1000*9.81*0.005
=5.95mm.

22. An oil of vicosity 7 poise is used for lubrication between shaft and sleeve. The diameter of shaft is 0.6 m and it rotates is 360 rpm. Calculate the power lost in oil for a sleeve length of 160mm. The thickness of oil film is 1.0mm
a) 25.31 kW
b) 50.62 kW
c) 37.97 kW
d) 12.65 kW
Explanation: Power lost= torque * angular velocity
= shear stress * area* radius* angular velocity
Shear Stress = viscosity* velocity gradient
Power lost= 7916.8*3.142*0.3*0.3*0.3*2*3.142*60
= 25.31 kW.

23. Find the capillarity rise or fall if a capillary tube of diameter .03m is immersed in hypothetical fluid with specific gravity 6.5, surface tension 0.25 N/m and angle of contact 147°.
a) 0.44mm fall
b) 0.88mm fall
c) 0.44mm rise
d) 0.88mm rise
Explanation: h=4*cosθ*σ/ρ*g*d
=4*cos147*0.25/6.5*1000*9.81*0.03
=-0.44 mm i.e 0.44 mm fall.

24. Will capillary rise occur and if it occurs what will be capillary rise if glass capillarity tube is immersed in water and experiment is carried out by astronauts in space.
a) Capillarity rise will not occur
b) Capillarity rise will occur infinitely and will come out in form of fountain
c) Capillarity rise will occur finitely and will be the whole length of tube
d) None of the mentioned
Explanation: Capillary rise is given by
h=4*cosθ*σ/ρ*g*d
hence rise is inversely proportional to g
In space g is 0 m/s2
Hence, capillarity rise will occur finitely and will be the whole length of tube.

25. The surface tension of fluid in contact with air at 25℃ is 0.51N/m. The pressure inside a droplet is to be 0.05 N/cm2 greater than outside pressure. Determine the diameter of the droplet of water.
a) 4.08mm
b) 8.16mm
c) 2.04mm
d) None of the mentioned
Explanation: P=4*σ/d
d= 4*.51/500
=4.08 mm.

26. If a fluid of certain surface tension and diameter is used to create a soap bubble and a liquid jet. Which of the two, bubble or liquid jet, will have greater pressure difference on the inside and outside.
a) Liquid jet
b) Soap bubble
c) Both will have same pressure differrence
d) None of the mentioned
Explanation: For soap bubble,
P=8*σ/d
For liquid jet,
P=2*σ/d
Hence, soap bubble will be having more pressure difference.

27. Capillarity fall is reduced if we take the appartus (capillary tube immersed in fluid having acute angle of contact) considerable distance inside the earth( i.e below the earth crust).
a) True
b) False
Explanation: Capillary rise is given by
h=4*cosθ*σ/ρ*g*d
Inside the earth, g (acceleration due to gravity) decreases. Hence, capillary rise will increase compared to that on the earth’s surface.

28. For liquid fluids will capillarity rise (or fall) increase or decrease with rise in temperature.
a) Increase
b) Decrease
c) Remain constant
d) First decrease then increase
Explanation: Capillary rise is given by
h=4*cosθ*σ/ρ*g*d
As temperature increases, σ(surface tension) decreases. Therefore, correspondingly rise(or fall) will decrease as their is direct proportional relation between the two.

29. Cavitation is more pronounced in rough pipes than smooth surfaced pipes.
a) True
b) False
Explanation: Rough surfaced pipes have more friction with the fluid and hence possibility of cavitation is more pronounced.

30. Which of the following is correct regarding the formation and collapse of vapor bubbles in a liquid?
a) Vapor bubbles are formed when the fluid pressure goes above the vapor pressure and collapses when the fluid pressure goes above the bubble pressure
b) Vapor bubbles are formed when the fluid pressure goes above the vapor pressure and collapses when the fluid pressure goes below the bubble pressure
c) Vapor bubbles are formed when the fluid pressure drops below the vapor pressure and collapses when the fluid pressure goes below the bubble pressure
d) Vapor bubbles are formed when the fluid pressure drops below the vapor pressure and collapses when the fluid pressure goes above the bubble pressure
Explanation: Whenever the absolute pressure of a fluid drops below it’s vapor pressure, bubble formation starts. Again, when the fluid pressure goes above the bubble pressure, it’ll collapse. This is how cavitation formation takes place.

31. Which of the following statement is true about vapor pressure of a liquid?
a) Vapor pressure is closely related to molecular activity and temperature of the liquid
b) Vapor pressure is closely related to molecular activity but independent of the temperature of the liquid
c) Vapor pressure is not affected by molecular activity and temperature of the liquid
d) Vapor pressure is not affected by molecular activity and is independent of the temperature of the liquid
Explanation: The vapor pressure of a liquid at a given temperature is given by the pressure ex-erted by the saturated vapor on the liquid surface. When the vapor is saturated, an equilibrium exists between the liquid and the vapor phases. The number of molecules leaving the liquid surface is equal to the number of molecules entering the liquid surface. Hence, it is obvious that vapor pressure will be related to molecular activity and consequently to temperature. With the increase in temperature molecular activity increases as a result of which vapor pressure increases.

32. Which of the following equation correctly depicts the relation between the vapor pressure of a liquid and it’s temperature?
a) Vapor pressure increases linearly with the increase in temperature of the liquid
b) Vapor pressure increases slightly with the increase in temperature of the liquid at low temperatures and the rate of increase goes high at higher temperatures
c) Vapor pressure increases rapidly with the increase in temperature of the liquid at low temperatures and the rate of increase goes low at higher temperatures
d) Vapor pressure remains unchanged with the increase in temperature of the liquid
Explanation: Vapor pressure is closely related to molecular activity which is in turn dependant on the temperature of the liquid. With the increase in temperature molecular activity of a vapor increases slowly at first and then rapidly. Similar is the nature of variaion of vapor pressure.

33. Which of the following is the condition for the boiling of a liquid?
a) Absolute pressure of a liquid must be greater than or equal to it’s vapor pressure
b) Absolute pressure of a liquid must be less than or equal to it’s vapor pressure
c) Absolute pressure of a liquid must be equal to it’s vapor pressure
d) Absolute pressure of a liquid must be greater than it’s vapor pressure
Explanation: As the absolute pressure of a liquid goes below it’s vapor pressure, the formation of vapor bubbles start. Thus, for boiling to start, the absolute pressure of a liquid must be less than or equal to it’s vapor pressure.

34. Which of the following machines have the possibility of cavitation?
a) Reaction turbines and centrifugal pumps
b) Reaction turbines and reciprocating pumps
c) Impulse turbines and centrifugal pumps
d) Impulse turbines and reciprocating pumps
Explanation: Cavitation occurs whenever absolute pressure of a liquid drops below it’s vapor pressure. Dropping of pressure is observed mainly in reaction turbines and centrifugal pumps.

35. The three liquids 1, 2, and 3 with vapor pressures V1, V2 and V3 respectively, are kept under same pressure. If V1 > V2 > V3, which liquid will start boiling early?
a) liquid 1
b) liquid 2
c) liquid 3
d) they will start boiling at the same time
Explanation: A liquid starts to boil whenever it’s absolute pressure drops below it’s vapor pressure. Thus, the absolute pressure of liquid 1 will drop early, as a result it’ll start boiling early.

36. Equal amount of a particular liquid is poured into three similar containers, namely 1, 2 and 3, at a temperature of T1, T2 and T3 respectively. If T1 < T2 < T3, the liquid in which container will have the highest vapor pressure?
a) container 1
b) container 2
c) container 3
d) the vapor pressure of the liquid will remain the same irrespective of it’s temperature
Explanation: Higher the temperature, higher is the molecular activity and consequently, higher is the vapor pressure of a given liquid. Since, container 3 is at the highest temperature, liquid in it will have the highest vapor pressure.

#### Module-2

1. What is the pressure in Pascals at a depth of 1m below the water surface?
a) 98100 Pa
b) 980 Pa
c) 98 Pa
d) 1 Pa
Explanation: It’s the summation of weights on top of the water surface. In this case, it is the weight of the atmosphere and water above 1m. [Formula: P (depth) = Patm +(density of water*gravitational constant*depth)].

2. 15 bar equals to __________ Pascals.
a) 105Pa
b) 1.5 x 106 Pa
c) 100 Pa
d) 1000 Pa
Explanation: Bar is a metric unit of pressure, but it does not fall under the SI units. One bar is exactly equal to a 100,000 Pascals. This value is taken from the atmospheric pressure on the earth at sea level.

3. The pressure at any given point of a non-moving fluid is called the ____________
a) Gauge Pressure
b) Atmospheric Pressure
c) Differential Pressure
d) Hydrostatic Pressure
Explanation: Hydrostatic pressure varies with the increase in depth. Hydrostatic pressure is measured from the surface of the fluid because of the increasing weight of the fluid. The fluid exerts a downward force from the surface of water thus making it a non-moving fluid.

4. The device used to measure the fluid pressure is _____________
a) Hygrometer
b) Calorimeter
c) Manometer
d) Thermometer
Explanation: Manometer is the most preferred measuring device as the pressure is measured by difference in the column heights of the manometer. It is expressed in terms of inches or centimeters of fluid making it easier for the conversion process.

5. What type of liquids are measured using a manometer?
a) Heavy liquids
b) Medium Liquids
c) Light Liquids
d) Heavy and light liquids
Explanation: Measurement of liquid in a manometer takes place through differential pressures by balancing the weight. Thus, it is easier for the manometer to measure liquids of lesser density than the heavier ones. Example of a light liquid is Water.

6. Which among these devices are the best suited for the measurement of high pressure liquids with high accuracy?
b) Vacuum Gauge
c) Manganin wire pressure
d) Ionization Gauge
Explanation: Manganin wire is the most suitable measurement device for high pressure liquids. It has a high stability and durability on a long term basis. It also has a high hydrostatic pressure sensitivity and low strain sensitivity.

7. How do we measure the flow rate of liquid?
a) Coriolis method
c) Conveyor method
d) Ionization method
Explanation: Coriolis concept of measurement of fluid takes place through the rotation with the reference frame. It is an application of the Newton’s Law. The device continuously records, regulates and feeds large volume of bulk materials.

8. What is the instrument used for the automatic control scheme during the fluid flow?
a) Rotameters
b) Pulley plates
c) Rotary Piston
d) Pilot Static Tube
Explanation: Pilot static tube is a system that uses an automatic control scheme to detect pressure. It has several holes connected to one side of the device. These outside holes are called as a pressure transducer, which controls the automatic scheme during fluid flow.

9. Define Viscosity?
a) Resistance to flow of an object
b) Resistance to flow of air
c) Resistance to flow of fluid
d) Resistance to flow of heat
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.

10. What is the viscosity of water at 30oC?
a) 80.1
b) 0 .801
c) 801
d) 0.081
Explanation: A graph is plotted with temperature in the x-axis and dynamic viscosity in the y-axis. With the increase in pressure the viscosity decreases. It corresponds to an informal concept of thickness.

11. A Hydraulic press has a ram of 30 cm diameter and a plunger of of 2 cm diameter. It is used for lifting a weight of 35 kN. Find the force required at the plunger.
a) 233.3 kN
b) 311.1 kN
c) 466.6 kN
d) 155.5 kN
Explanation: F/a=W/A
F=(35000*3.142*.02*.02)/(3.142*0.3*0.3)
=155.5 kN.

12. The pressure at a point in the fluid is 4.9 N/cm2. Find height when the fluid under consideration is in oil of specific gravity of 0.85.
a) 5.83 m
b) 11.66 m
c) 17.49 m
d) 8.74 m
Explanation: Height=p/ρg
=48620/850*9.81
=5.83 m.

13. An open tank contains water upto a depth of 350 cm and above it an oil of specific gravity 0.65 for a depth of 2.5 m. Find the pressure intensity at the extreme bottom of the tank.
a) 5.027 N/cm2
b) 10.05 N/cm2
c) 2.51 N/cm2
d) None of the mentioned
Explanation: p= (specific gravity of water* height of water + specific gravity of oil* height of oil) * 9.81
= 5.027 N/cm2.

14. The diameters of a small piston and a large piston of a hydraulic jack are 45 mm and 100 mm respectively.Force of 0.09 kN applied on smaller in size piston. Find load lifted by piston if smaller in size piston is 40 cm above the large piston. The density of fluid is 850 kg/m3
a) 60 N/cm2
b) 12 N/cm2
c) 30 N/cm2
d) None of the mentioned
Explanation: Pressure at bottom of tank =ρgh + F/a
=850*9.81*0.4 + 90/3.142*0.045*0.045
=60 N/cm2.

15. If fluid is at rest in a container of a narrow mouth at a certain column height and same fluid is at rest at same column height in a container having broad mouth, will the pressure be different at certain depth from fluid surface.
a) Pressure will be same for both.
b) Pressure will be more for narrower mouth
c) Pressure will be less for narrower mouth
d) None of the mentioned
Explanation: As per hydrostatic law, the pressure depends only on the height of water column and not its shape.

16. We can draw Mohr’s circle for a fluid at rest.
a) True
b) false
Explanation: Mohr’s circle is used to denote shear stress distribution. For fluid at rest, there is no shear stress. Hence, we cannot draw Mohr’s circle for fluid at rest.

17. Pressure intensity or force due to pressure gradient for fluid at rest is considered as which kind of force?
a) Surface force
b) Body force
c) Force due to motion
d) None of the mentioned
Explanation: Pressure force is surface force.

18. Calculate the hydrostatic pressure for water moving with constant velocity at a depth of 5 m from the surface.
a) 49 kN/m2
b) 98 kN/m2
c) since fluid is in motion, we cannot analyse
d) None of the mentioned
Explanation: If fluid is moving with uniform velocity we treat it analytically same as if fluid is at rest
p= ρgh.

19. Pressure distribution for fluid at rest takes into consideration pressure due to viscous force.
a) True
b) False
Explanation: Viscous force term in pressure expression for fluid at rest is absent as their is no motion of liquid.

20. Barometer uses the principle of fluid at rest or pressure gradient for its pressure calculation.
a) True
b) False
Explanation: Principle of Barometer is Hydrostatic law.

21. The right limb of a simple U-tube manometer containing mercury is open to the atmosphere while the lift limb is connected to a pipe in which a fluid of specific gravity 0.85 is flowing. The centre of the pipe is 14 cm below the level of mercury in the right limb.Evaluate the pressure of fluid flowing in the pipe if the difference of mercury level in the two limbs is 22 cm.
a) 2.86 N/cm2
b) 5.73 N/cm2
c) 1.43 N/cm2
d) None of the mentioned
Explanation: Pressure at centre of pipe + Pressure at depth 8 cm in left limb = Pressure at depth 22 cm in right limb
P = 13600×9.81×0.22 – 850×9.81×.08
= 2.86 N/cm2.

22. A single coloumn manometer is connected to a pipe containing a liquid of specific gravity 0.75. Find the pressure in the pipe if the area of reservoir is 250 times the area of tube for the manometer reading. The difference in mercury level is 40 cm. On the left limb the fluid is upto the height of 20 cm.
a) 10.42 N/cm2
b) 5.21 N/cm2
c) 2.60 N/cm2
d) None of the mentioned
Explanation: Pressure = a/A height × (density of mercury × 9.81-density of fluid × 9.81)+ height in right limb × density of mercury × 9.81 – height in left limb × density of fluid × 9.81
= 5.21 N/cm2
{ Here a/A = 1/ 250}.

23. A Differential manometer is connected at the points A and Bat the centre of two pipes. The pipe A(left limb) contains a liquid of specific gravity = 1.5 while pipe B (right limb)contains a liquid of specific gravity 0.85. The pressure at A and B are .5 kgf/cm2 and 1.2 kgf/cm2 respectively. Find the difference in level of mercuru in the differential manometer. A is 2.5m above B and 5 m above the mercury in its own limb. B is 2.5 m above the mercury level in limb A.
a) 12.7 cm
b) 25.5 cm
c) 6.28 cm
d) 10.85 cm
Explanation: Total pressure at the datum line in limb A = Total pressure at the datum line in limb B\
0.5*9.81*10000 + 5*9.81*1500 + h*9.81*13600 = 1.2*9.81*10000 + (h+2)*9.81*850
After solving,
h=12.7 cm.

24. An inverted differential manometer is connected to two pipes A and B which covey water. The fluid in manometer is oil of specific gravity 0.75. For the manometer readings, find the pressure difference between A and B. Datum in left limb is 40 cm above point A. Point B is 60 cm below datum line. Difference in level of fluid is 20 cm.
a) 1471 N/m2
b) 2943 N/m2
c) 735.75 N/m2
d) None of the mentioned
Explanation: Total pressure at the datum line in limb A = Total pressure at the datum line in limb B
Pressure difference between A and B = -0.4*9.81*100 + 0.2*9.81*750 + 0.4*9.81*1000
= 1471 N/m2.

25. In the inverted U-tube Differential manometer, how is the specific gravity of manometric fluid used relative to the fluid flowing in the pipes
a) Specific gravity is more than that of fluid flowing in pipes
b) Specific gravity is less than that of fluid flowing in pipes
c) Specific gravity is equal to that of fluid flowing in pipes
d) None of the mentioned
Explanation: In the inverted U-tube Differential manometer, specific gravity of manometric fluid used is less than relative to the fluid flowing in the pipes as the manonmetric fluid is at the top.

26. Why is large reservoir used in single column manometer?
a) In order to enhance the change in level of liquid in reservoir
b) In order to negate the effects of change in level due to pressure variation
c) In order to reduce the effect due to dynamic pressure variation due to motion
d) None of the mentioned
Explanation: Single column manometer directly gives the pressure by measuring the height in the other limb and due to large cross sectional area of the reservoir, for any variation in pressure, the change can be neglected.

27. Manometers are the pressure measuring devices which use the principle of dynamic pressure to measure the pressure difference.
a) True
b) False
Explanation: Manometers are the pressure measuring devices which use the principle of pressure due to static fluid (i.e the column height) to measure the pressure difference.

28. The distance moved by liquid will be more in which type of manometer?
a) Inclined Single coloumn manometer
b) Vertical Single coloumn manometer
c) Horizontal Single coloumn manometer
d) None of the mentioned
Explanation: The distance moved by liquid will be more in Inclined Single column manometer due to its inclination.

29. Differential manometer gives the pressure reading with respect to atmospheric pressure.
a) True
b) False
Explanation: Differential manometer gives the pressure difference between the fluid flowing in two pipes with respect to each other.

30. Which device is popularly used for measuring difference of low pressure?
a) Inverted U-tube Differential Manometer
b) U-tube Differential Manometer
c) Inclined Single column manometer
d) Vertical Single column manometer
Explanation: Inverted U-tube Differential Manometer has lighter manometric fluid, Hence it is used for measuring the low pressure difference.

31. Does total pressure takes into the account force exerted by the fluid when it is in the dynamic motion?
a) Yes
b) No
c) Depends on the conditions
d) Depends on the type of Motion
Explanation: Total pressure is defined only for the static fluid at rest. There is no dynamic component as no motion is involved.

32. Can centre of pressure for a vertical plane submerged surface be ever be above centre of Gravity
a) Yes
b) No
c) It can be above in cases where the surface height is very large
d) None of the mentioned
Explanation: Centre of pressure always lies below the centre of gravity. In certain cases it may coincide but it can never be above the centre of gravity.

33. Which principle is used for calculating the centre of pressure?
a) Principle of momentum
b) Principle of conservation of energy
c) Principle of balancing of momentum
d) None of the mentioned
Explanation: We balance the moment in order to calculate the position of centre of pressure.

34. In a vertically submerged plane surface, pressure at evbery point remains same
a) True
b) False
Explanation: Pressure at every point is different as the depth of different point from is different.

35. The magnitude of total pressure and centre of pressure is independent on the shape of the submerged plane surface.
a) True
b) False
Explanation: For differently shaped surfaces, the area and hence position of centroid will be different. Hence, the magnitude of total pressure and centre of pressure is dependent on the shape of the submerged plane surface.

36. A circular plate 5.0 m diameter is immersed in such a way that its greatest and least depth below the free surface are 3 m and 1 m respectively. determine the position of the centre of pressure.
a) 2.5 m
b) 5 m
c) 4.5 m
d) 6 m
Explanation: centre of pressure, ŷ=I*sin²θ/Aĥ + ĥ
…….ĥ=(y+dsinθ)
=3.142*2.54*sin²23.58/3.142*2.52*(1+2.5sin23.58)+*(1+2.5sin23.58)
=2.5 m.

37. For an inclined plate the pressure intensity at every point differs.
a) True
b) False
Explanation: Due to inclination the depth of every point is different from the free liquid surface. Hence, the pressure intensity varies with depth.

38. The pressure intensity for a horizontal plate is maximum on the surface of the earth and decreases as we move further away from the surface of the earth either downward or upward.
a) True
b) False
Explanation: As we move away from the surface of the earth either downward or upward g decreases, w decreases. Hence pressure intensity decreases.

39. For an inclined plane for which position, maximum total pressure acts on it.
a) Horizontal
b) Vertical
c) Inclined
d) None of the mentioned
Explanation: Total pressure, F=w*a*ŷ=w*A*(y+dsinθ)
For vertical plate, θ=90⁰
Hence, total pressure is maximum.

40. The total pressure or pressure intensity is zero for any point on inclined surface in space.
a) True
b) False
Explanation: Total pressure, F=w*a*ŷ
In space, w=0 as g=0
Hence, f=0.

41. In case of spherical bodies with uniform mass distribution, what is the position of center of pressure relative to centre of gravity.
a) Above
b) Below
c) Coincides
d) None of the mentioned
Explanation: In case of spherical bodies with uniform mass distribution, centre of pressure coincides with centre of gravity.

42. Find the position of centre of buoyancy for a wooden block of width 3.5 m and depth 1 m, when it floats horizontally in water. The density of wooden block id 850 kg/m3 and its length 7.0 m.
a) 0.95
b) 0.85
c) 1.05
d) 1.65
Explanation: Weight of the block=ρ*g*Volume=850*9.81*7*3.5*1=204.29 kN
Volume of
water displaced= Weight of water displaced/weight density of water
= 20.825 m3.
h=20.825/3.5*7=0.85 m.

43. A stone weighs 450 N in air and 200 N in water. Compute the volume of stone.
a) .025 m3
b) .05 m3
c) .075 m3
d) None of the mentioned
Explanation: Weight of water displaced=Weight of stone in air – Weight of stone in water
=250
Volume of water displaced=Volume of stone=250/9.81*1000=0.025 m3.

44. A stone weighs 650 N in air and 275 N in water. Compute its specific gravity.
a) 1.73
b) 2.45
c) 3.46
d) 0.865
Explanation: Weight of water displaced=Weight of stone in air – Weight of stone in water
=375
Volume of water displaced=Volume of stone=375/9.81*1000=0.038 m3
Density of stone= mass/volume=650/9.81*0.038=1733 kg/m3
specific gravity= Density of stone/Density of water=1.73.

45. A body of dimensions 2.7 m * 3.8 m * 2.5 m, weighs 2500 N in water.Find its weight in air.
a) 254.12 kN
b) 508.25 kN
c) 101.65 kN
d) 127.06 kN
Explanation: Weight of stone in air = Weight of water displaced+Weight of stone in water
= 9.81*1000*2.7*3.8*2.5+2500=254.12 kN.

46. Find the density of metallic body which floats at the interface of mercury of sp.gr 13.6 and water such that 40 % of its volume is sub-merged in mercury and 60% in water.
a) 6040 kg/m3
b) 12080 kg/m3
c) 24160 kg/m3
d) 3020 kg/m3
Explanation: Total Bouyant force=Force of bouyancy due to water+Force of bouyancy due to mercury
For equilibrium, Total bouyant force= Weiht of body
1000*9.81*0.6*V + 13.6*1000*9.81*0.4*V=ρ*g*V
ρ=6040 kg/m3.

47. What is the principal cause of action of buoyant force on a body submerged partially or fully in fluid?
a) Displacement of fluid due to submerged body
b) Development of force due to dynamic action
c) Internal shear forces mitigating external forces
d) None of the mentioned
Explanation: The principal cause of action of buoyant force on a body submerged partially or fully in fluid is the force equal in magnitude to the weight of the volume of displaced fluid.

48. How can relatively denser object be made to float on the less dense fluid?
a) By altering the shape.
b) By altering the forces acting on the object
c) By altering the shear forces acting on the object
d) None of the mentioned
Explanation: By changing the shape of an object it can be made to float on a fluid even if it is denser than that fluid. This principle is used in ship building.

49. What happens to the buoyant force acting on the airship as it rises in the air?
a) Buoyant force increases
b) Buoyant force decreases
c) Buoyant force remains constant
d) Buoyant force first increases then shows decrease
Explanation: Buoyant force acting on the airship decreases as it rises in the air as air at higher altitude becomes rarer and its density decreases.

50. As a balloon rises in the air its volume increases, at the end it acquires a stable height and cannot rise any further.
a) True
b) False
Explanation: As balloon rises in air, pressure acting on it reduces and therefore its volume increases. Also, a rising balloon ceases rising when it and the displaced air are equal in weight.

51. Submarines use principle of ‘neutral buoyancy’ to go into the water.
a) True
b) False
Explanation: To dive, the submarine tanks are opened to allow air to exhaust, while the water flows in. When the weight has been balanced so the overall density of the submarine is equal to the water around it, it has neutral buoyancy and hence will go down.

52. In case of spherically shaped bodies of uniform mass distribution and completely immersed in fluid and floating, the centre of buoyancy coincides with centre of gravity.
a) True
b) False
Explanation: The volume of fluid displaced by the body is equal to the actual volume of body in air. Hence, In case of spherically shaped bodies of uniform mass distribution and completely immersed in fluid and floating, the centre of buoyancy coincides with centre of gravity.

53. Proper explanation for metacentre is:
a) Point at which line of action of force meets the normal axis of body when it is given angular displacement
b) Intersection of line passing through new centre of buoyancy and centre of gravity.
c) point about which body starts oscillating when it is given small angular displacement
d) All of the mentioned
Explanation: All of the above explanation are apt.

54. The metacentric height is affected by the change in density.
a) True
b) False
Explanation: Metacentre does depend on the density. Hence, the metacentric height is affected by the change in density.

55.For a completely immersed body, the metacentric height is always zero.
a) True
b) False
Explanation: The metacentric height may or may not be zero as metacentre will not always coincide with centre of gravity.

56. Meta centre always lies below the centre of gravity
a) True
b) False
Explanation: It depends on the stability of floating body.

57. The principle of floatation of bodies is based on the premise of
a) Metacentre
b) Newtons first law
c) Newtons law of viscosity
d) None of the mentioned
Explanation: The principle of floatation of bodies is based on the premise of Metacentre.

#### Module-3

1. Which method is used exclusively in fluid mechanics?
a) Lagrangian method
b) Eulerian method
c) Both Lagrangian and Eulerian methods
d) Neither Lagrangian nor Eulerian method
Explanation: In Fluid Mechanics, the matter of concern is the general state of motion at various points in the fluid system (as in Eulerian approach) rather than the motion of each particle (as in Lagrangian approach). Hence, the Eulerian method is extensively used in Fluid Mechanics.

2. What type of flow can be taken for granted in a pipe of a uniform cross-section?
c) uniform
d) non-uniform
Explanation: According to the continuity equation, ρAV =constant, where ρ= density, A= cross-sectional area of flow, V = velocity of flow. For a pipe of a uniform cross-section, no matter what the rate of flow is, the velocity of flow inside the pipe will always remain constant. Hence, it’ll always be a uniform flow. It’ll be a steady flow if and only if the water level is maintained at a constant level by supplying water at the same rate as it gets discharged, else the water level will keep decreasing with time leading to an unsteady flow.

3. Can the flow inside a nozzle be steady and uniform?
a) yes
b) never
c) it can be steady but never uniform
d) it can be uniform but never steady
Explanation: According to the continuity equation, ρAV =constant, where ρ= density, A= cross-sectional area of flow, V = velocity of flow. For a nozzle, the area gradually decreases towards it’s exit. Thus, no matter what the rate of flow is, the velocity of flow at the nozzle exit will always be greater than that at it’s entrance. Hence, it’ll always be an unsteady flow. It can be a steady flow if and only if the water level is maintained at a constant level by supplying water at the same rate as it gets discharged, else the water level will keep decreasing with time leading to an unsteady flow.

4. Which of the following statements is true regarding one and two-dimensional flows?
a) Flow in a pipe is always taken as one-dimensional flow
b) Flow in a pipe is always taken as two-dimensional flow
c) Flow in a pipe is taken as one-dimensional flow when average flow parameters are considered
d) Flow in a pipe is taken as two-dimensional flow when average flow parameters are considered
Explanation: The flow inside a pipe can be described by the cylindrical co-ordinate system (r; θ; z), where r is in the radial direction, θ in the angular direction and z in the axial direction. For a circular cross-sections, the flow can be taken to be independent of θ. Hence, it can be taken aa a two-dimensional flow. Again if aerage flow parameters are considered to account for the variation in the radial direction, the flow can be taken as an one-dimensional flow.

5. Which of the following is true?
a) Flow is rotational inside the boundary layer and irrotational outside
b) Flow is irrotational inside the boundary layer and rotational outside
c) Flow is rotational both inside and outside of the boundary layer
d) Flow is irrotational both inside and outside of the boundary layer
Explanation: When a torque is applied to a fluid particle, it undergoes a rotation. Thus, the rotation of a fluid particle will alwayds be associated with shear stress. Shear stress is in turn dependent on the viscosity. Hence, rotational flow occurs where the viscosity effects are predominant. Since, viscosity effects are predominant inside the blundary layer, the flow will be rotational in this region. However, outside the boundary layer, the viscosity effects are negligible. Hence, flow can be treated as irrotational outside the boundary layer.

6. Which of the following is true?
a) Flow is laminar inside the boundary layer and turbulent outside
b) Flow is turbulent inside the boundary layer and laminar outside
c) Flow is laminar both inside and outside of the boundary layer
d) Flow is turbulent both inside and outside of the boundary layer
Explanation: Flows can be characterized as laminar or turbulent on the basis of Reynold’s number Re = ρvd / μ, where ρ is the density, d is the pipe diameter and μ is the viscosity. For Re < 2000, the flow will be laminar and Re > 4000, the ow will be turbulent. For laminar flow, the viscosity effects must be high (μ should be high) as inside the boundary layer. Outside the boundary layer, the viscosity effects are negligible. Hence, the flow will be turbulent.

7. “The velocity of entrance and exit through a nozzle remains the same.” Is this ever possible?
a) only if the flow is compressible
b) only if the flow is laminar
c) only if the flow is rotational
d) never possible
Explanation: According to the continuity equation, ρAV =constant, where ρ= density, A= cross sectional area of flow, V = velocity of flow. If v =constant, ρA =constant. Thus a change is A will mean a change in ρ. Hence, the flow is possible only if the fluid is compressible.

8. 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
Explanation: 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.

9. 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
Explanation: Continuity equation is based on the the principle of conservation of mass.

10. The continuity equation is only applicable to incompressible fluid.
a) True
b) False
Explanation: The continuity equation is only applicable to incompressible as well as compressible fluid.

11. 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
Explanation: According to continuity equation,
Area × velocity = constant
Hence, as area decreases velocity increases.

12. 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
Explanation: According to continuity equation,
ρ*A*v = constant
Hence, as density and area decreases velocity is bound to increase.

13. 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
Explanation: In majority of the fluid flow problems, flow is assumed to be steady.

14. 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
Explanation: According to continuity equation,
Area × velocity = constant
Area1*Velocity1 = Area2*Velocity2
Velocity2=(Area1*Velocity1)/Area2
= (82 * 6) / 132=2.27 m/s.

15. The continuity equation can only be used for analysis of conserved quantity.
a) True
b) False
Explanation: Continuity equation is defined on a control volume and hence, is applicable only to Conserved quantities.

16. 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
Explanation: According to continuity equation,
Area × velocity = constant
Area1*Velocity1 = Area2*Velocity2
(Area1*Velocity1)/Velocity2=Area2
Area 2= 33.93 m2.

17. 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
Explanation: Fluid flow must satisfy equation of conservation of mass or continuity equation, for itto be physically possible.

18. Continuity equation can also be derived for polar coordinate system
a) True
b) False
Explanation: Continuity equation in polar coordinate is also used for analysis.

19. The characteristic of Ideal fluid are
a) Incompressible
b) Inviscid
c) Fluid velocity is uniform
d) Shear stress has a constant, non zero value
Explanation: As ideal fluid is inviscid, shear stress is zero.

20. Which of the following is not a case of ideal fluid flow?
a) Forced vortex Flow
b) Uniform Flow
c) Sink Flow
d) Superimposed flow
Explanation: Forced vortex Flow does not satisfy the characteristic of ideal fluid flow.

21.What is a special characteristic of uniform flow parallel to X axis?
a) Velocity is constant
b) Acceleration is constant
c) X- component of velocity is constant
d) None of the mentioned
Explanation: Velocity is constant in uniform flow.

22. The source flow is flow coming from a point and moving out in a circular manner.
a) True
b) False
Explanation: The source flow is flow coming from a point and moving out in a radial manner.

23. The sink flow is flow in which fluid moves radially inwards towards a point where it disappears at a variable rate.
a) True
b) False
Explanation: The sink flow is flow in which fluid moves radially inwards towards a point where it disappears at a constant rate.

24. The pattern for streamlines and equipotential lines is different for source and sink flow.
a) True
b) False
Explanation: The pattern for streamlines and equipotential lines is different for source and sink flow.

25. In free vortex flow, the flow is linear in nature.
a) True
b) False
Explanation: In free vortex flow, the flow is circular in nature.

26. What is the nature of streamlines of free vortex flow?
a) Concentric
b) Non-concentric
c) Linear
d) None of the mentioned
Explanation: The nature of streamlines of free vortex flow is concentric.

27. For source flow, the radial velocity increases as we move radially outward.
a) True
b) False
Explanation: There is an inverse relation between velocity and radial distance for source flow.

28. When is air assumed to be incompressible?
a) At low speed
b) At high speed
c) Independent of its speed
d) None of the mentioned
Explanation: Air is assumed to be incompressible at low speed.

29. When a uniform flow is flowing through a doublet, resultant flow obtained is
a) Flow past a Rankine oval of equal axes
b) Flow past a circular cylinder
c) All of the mentioned
d) None of the mentioned
Explanation: They both mean the same thing. They are different ways of interpreting the same phenomenon.

30. How many stagnation points are present in a source and sink pair in a uniform flow
a) Two
b) Three
c) One
d) None
Explanation: There are two stagnation points are present in a source and sink pair in a uniform flow.

31. Which of the following is not a type of superimposed flow?
a) Source and sink pair in uniform flow.
b) Double flow
c) A source and sink pair in turbulent flow.
d) A plane source in uniform flow
Explanation: There is no such kind of superimposed flow.

32. In the equation for steam function due to source steam function is inversely proportional to magnitude at discharge
a) True
b) False
Explanation: Steam function is directly proportional to magnitude of discharge.

33. Streamlines of doublet flow are family of circles tangent to a common axis.
a) True
b) False
Explanation: This is special characteristic of doublet flow.

34. What is the characteristic of stagnation point
a) Velocity is zero
b) Acceleration is uniform
c) Velocity is zero
d) Acceleration is zero
Explanation: At stagnation point velocity is zero, as the fluid comes at rest. This characteristic at stagnation point.

35. Potential lines for the source-sink pair will be eccentric non intersecting circles with their centers on the axis.
a) True
b) False
Explanation: The potential line for the source sink pair will be eccentric non intersecting circles with their centers on the axis.

36. What is the term used for a case where source and sink( both of them are of equal magnitude) approach each other such, distance between them reduces and product of distance and discharge magnitude remains constant.
a) A plain pair
b) A doublet source in uniform
c) Hagen Poiseuille flow
d) Coutte flow
Explanation: This is a special case of superimposed flow called double flow.

37. What type of flow is obtained by superimposing two definite flow types{( considering ideal condition)
a) Ideal
b) Potential
c) Both
d) None of the mentioned
Explanation: Any linear combination of two different types of flows will result in a potential and ideal flow.

38. The nature of streamlines in a flow net obtained by the combination of source and sink is-
a) Linear
b) Curvilinear
c) Circular
d) Random
Explanation: The combination of the source and sink would result in a flow net where streamlines will be circular axes.

#### Module-4

1. Which of the following is NOT a type of force considered in the Navier-Stokes equation?
a) Gravity force
b) Pressure force
c) Surface tension force
d) Viscous force
Explanation: Gravity, Pressure force and viscous forces together constitute the derivation of the Navier-Stokes equation. Though surface tension force act on a fluid in motion, it is considered to be negligible for the Navier-Stokes equation.

2. Which of the following equations is a result of momentum conservation for inviscid steady flows?
a) Bernoulli’s equation
b) Navier-Stokes equation
c) First law of thermodynamics
d) Euler’s equation
Explanation: Bernoulli’s equation is an energy conservation equation which is obtained by integration of the Euler equation. Navier-Stokes equation is a force balance equation. The first law of thermodynamics is an energy conservation equation, too. Euler’s equation is a momentum equation. This equation is valid for inviscid steady flows.

3. The Bernoulli’s equation in fluid dynamics is valid for _________
a) Compressible flows
b) Transient flows
c) Continuous flows
d) Viscous flows
Explanation: To answer this equation, we need to know the assumptions used in Bernoulli’s equation. The Bernoulli’s theorem is only valid for ideal, steady, incompressible, continuous, inviscid and irrotational flows. So, out of the options, only continuous flows fit in the assumptions.

4. A water flows through a pipe at a velocity 2 m/s. The pressure gauge reading is 2 bar. The datum head is given to be 2 m. Find the piezometric head. (Assume all Bernoulli’s assumptions, Density of water = 1000 kg/m3, g = 9.8 m/s2).
a) 22.4 m
b) 22.6 m
c) 20.4 m
d) 20.6 m
Explanation: Piezometric head is the addition of pressure head and the datum head. The pressure head is given by P/ρg = 20.4 m. The datum head is 2 m, which makes it a total of 22.4 m. The velocity given is extra information.

5. A student wishes to find the velocity of air flowing through a pipe. He has a pressure gauge which displays only the dynamic pressure. The pressure gauge reads 0.018 mm Hg. Assume density of air to be 1.225 kg/m3, find the velocity V of air (ρHg = 13600 kg/m3).
a) 4 m/s
b) 2 m/s
c) 20 m/s
d) 40 m/s
Explanation: (0.018 mm Hg * 13.6 * 9.8) = 2.4 bar. Dynamic pressure is given by ρV2/2. Equating 2.4 bar with dynamic pressure gives V = 2 m/s.

6. If compressibility force and surface tension force are neglected from the Newton’s second law of motion, which of the following equations result?
a) Navier-Stokes equation
b) Euler’s equation
c) Bernoulli’s equation
d) Reynolds equation
Explanation: The Newton’s second law of motion comprises of 6 forces, namely, gravity, viscosity, pressure, turbulence, surface tension and compressibility forces. Reynolds equation comprises of 4 forces. Surface tension force and compressibility forces are neglected for finding Reynolds equation.

7. What does a pitot tube measure? Upon which principle does a pitot tube work?
a) Pressure, Bernoulli’s principle
b) Velocity, Bernoulli’s principle
c) Pressure, Euler’s equation
d) Velocity, Euler’s equation
Explanation: Even though a pitot tube may be primarily used to find velocity of a fluid, the Pitot tube measures pressure and not velocity. The Pitot tube works upon the Bernoulli’s principle as it gives us pressure heads.

8. The best place to place a pitot tube on an aircraft for velocity measurement is just behind the jet engine.
a) True
b) False
Explanation: Pitot tube is used for velocity measurement or airspeed measurement of an aircraft. Placing a pitot tube behind the jet engine will give us the speed of the gas rejected by the jet engine instead of the airspeed, hence, giving us erroneous readings. The best placement would be at a point where the speed of air is closest to the airspeed as seen by the aircraft.

9. Navier- Stokes equation describes the motion of __________
a) Solid substance
b) Non-viscous fluid
c) Viscous fluid
d) Gas
Explanation: The equation described by Navier- Stokes is for a viscous fluid. The balanced equation arises from Newton’s Second Law of fluid motion. It assumes that the stress in the fluid is equal to the sum of a diffusing viscous term and a pressure term.

10. Froude number depends upon_________
a) Flow velocity, external field and characteristic length
b) Flow velocity and mass
c) Mass flow rate and volume
d) Characteristic length and volume
Explanation: The Froude number is a dimensionless number. It is defined as the ratio of flow inertia to the external field. The Froude number is based on the speed-length ratio.

11. Continuum mechanics is a branch of mechanics that deals with________
a) Fluid particles
b) Discrete particles
c) Kinematics and mechanical behaviour
d) Hydrostatic Pressure
Explanation: Continuum mechanics is a branch that deals with the analysis of kinematics and mechanical behaviour of materials. It can be modelled as a continuous mass rather than as discrete particles.

12. Which among the following cannot be used as an alternative term for a “solenoidal vector field”?
a) Incompressible vector field
b) Divergence- free vector field
c) Transverse vector field
d) Continuous random field
Explanation: A random field comes under a stochastic process. It can take up values that are multidimensional vectors or points on some manifold. A random field is a list of random numbers whose indices are identified with a discrete set of points in space.

13. The Navier- Stokes equation can be used in which of the following applications?
a) Automobiles
b) Ocean Currents
c) Airplanes
d) Thermometer
Explanation: An ocean current is a continuous direct movement of seawater. Ocean currents are forces generated by acting upon the mean flow. Therefore, ocean currents satisfy Navier-Stokes equation as they have a primary horizontal water movement.

14. Which among the following is not an example of magneto fluids?
a) Plasma
b) Liquid metals
c) Salt water
d) Alcohol
Explanation: Alcohol is an organic compound on which a hydroxyl functional group is bounded to a saturated carbon atom. Alcohols work as an antifreeze solution at cool temperatures. Thus, it is not a magneto fluid.

15. What is the velocity profile for Poiseuille flow?
a) Zero
b) Constant
c) Linear
Explanation: The velocity profile for Poiseuille flow is zero at either side of the channel and non-zero in the middle. Therefore, Quadratic equation is the only possible option here.

16. What are the Newtonian constitutive assumptions regarding relationship between stress tensor and velocity gradients?
a) Linear and isotropic
b) Constant
c) Linear
d) Non-Uniform
Explanation: Newtonian fluid is a fluid in which the viscous stresses arise due to its flow. The flow experiences a strain rate at every point. The strain rate is related to the constant viscosity tensor that does not depend upon the stress and velocity of the flow. Thus, the relationship is linear and isotropic.

17. What is the incompressibility condition in Navier-Stokes equation?
a) ∇.u=0
b) ∇.u>0
c) ∇.u<0
d) ∇.u=1
Explanation: This comes from the relation between the divergence of the flow. It also relates the Jacobian transformation with Lagrangian and Eulerian coordinates. Thus, ∇.u=0.

18. The velocity profile of the Couette flow is _______
b) Constant
c) Linear
d) Zero
Explanation: Couette flow is a flow of viscous fluid in the space between two surfaces. One surface moves tangentially with respect to the other. The configuration often takes the form of the two parallel plates or the gaps in between two cylinders.

19. When a cricket bat hits a cricket ball, impulse is applied on the_________
a) Bat
b) Ball
c) Bat and ball
d) No impulse is applied
Explanation: Time passes as force is applied on an object. The bat applies the force on the ball for a short period of time. By this way, we can say in accordance to the Newton’s third law forces come in pairs. So, the ball also applies a force on the bat, therefore it has an impulse applied to it.

20. Momentum is a ______ quantity
a) Scalar
b) Vector
c) Infinite
d) Zero
Explanation: Momentum is a vector quantity as it has both size and direction. Size of the momentum is equal to the mass of the object into the size of the objects velocity. The direction of objects velocity is the same as the direction of the momentum.

21. The equation for impulse is_______
a) F∆t=m∆v
b) F∆t=mu
c) F∆t=mT
d) F∆t=mRT
Explanation: Impulse is equal to the net force times the length of time over which the force is applied on the body of the fluid. On the right hand side, we have the change in momentum. Thus, option ‘a’ is the most suitable one.

22. What is the SI unit of impulse?
a) N/m
b) N/m2
c) N.s
d) Kg.m
Explanation: The SI unit of impulse is Newton second. It is given by the linear momentum due to the vector change. This produces an impulse in the same direction with respect to a given time.

23. What is the SI unit of momentum?
a) kgm/s
b) kgm/s2
c) kgm/s3
d) kg.m2
Explanation: The SI unit of momentum is given by the product of the units of mass and velocity. In SI units, (mass is in kg) and (velocity is in m/s). As we know that momentum is mass times velocity. The unit turns out to be kgm/s.

24. Change in momentum of an object is equal to the_______
a) Internal Energy
b) Entropy
c) Impulse
d) Enthalpy
Explanation: The mass is distributed over two velocities. According to the Newton’s second law, the change in momentum is equal to the impulse so produced. Since, momentum is a quantity that describes an object’s resistance to stopping. It is equated with its impulse.

25. Angular momentum is a _______ quantity
a) Scalar
b) Vector
c) Infinite
d) Finite
Explanation: Angular momentum is a vector quantity as it has both size and direction. Size of the momentum is equal to the mass of the object into the size of the object’s velocity. The direction of objects velocity is the same as the direction of the momentum.

26. Angular momentum is proportional to __________
a) Inertia and angular speed
b) Mass and angular speed
c) Angular speed and volume
d) Rate of change of angular speed
Explanation: Moment of inertia is not only dependent on the amount of matter. It also depends upon the position of axis of rotation and the shape of the matter. (Formula: L=Iω). Thus, inertia and angular speed play an important role in determining the angular momentum.

27. Which is the cheapest device for measuring flow / discharge rate.
a) Venturimeter
b) Pitot tube
c) Orificemeter
d) None of the mentioned
Explanation: Orificemeter is the cheapest available device for measuring flow/discharge rate.

28. The principle of Orificemeter is same as that of Venturimeter.
a) True
b) False
Explanation: The working principle for both Orificemeter and Venturimeter is same.

29. What is the relationship between Orificemeter diameter and pipe diameter
a) Orificemeter diameter is 0.5 times the pipe diameter
b) Orificemeter diameter is one third times the pipe diameter
c) Orificemeter diameter is one fourth times the pipe diameter
d) Orificemeter diameter is equal to the pipe diameter
Explanation: None.

30. The Orificemeter readings are more accurate than Venturimeter.
a) True
b) False
Explanation: The Venturimeter readings are more accurate than Orificemeter.

a) True
b) False
Explanation: The Pitot tube readings are more accurate than Orificemeter.

32. The Orificemeter has a smooth edge hole.
a) True
b) False
Explanation: The Orificemeter has a rough edge hole.

33. A nanometre is connected to a section which is at a distance of about 4 to 6 times the pipe diameter upstream from orifice plate.
a) True
b) False
Explanation: A manometre is connected to a section which is at a distance of about 1.5 to 2.0 times the pipe diameter upstream from orifice plate.

34. Venturimeter is based on integral form of Euler’s equation.
a) True
b) False
Explanation: Venturimeter is based on Bernoulli’s equation.

35. Orifice Meter can only be used for measuring rate of flow in open pipe like structure.
a) True
b) False
Explanation: Orificemetre can only be used for measuring rate of flow in an enclosed pipe like structure.

36. Orifice meter consists of a flat rectangular plate.
a) True
b) False
Explanation: Orifice meter consists of a flat circular plate.

37. 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
Explanation: It is the correct parametric definition for ‘large orifice’.

38. In case of any orifice, velocity always remains constant and hence discharge can be calculated.
a) True
b) False
Explanation: In case of large orifice, velocity always remains variable and hence discharge cannot be calculated.

39. 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
Explanation: The time taken to empty the tank is dependent on Cd as well as depends only on the height and acceleration due to gravity.

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

41. In case of submerged orifice the discharge is substantially dependent on temperature of fluid
a) True
b) False
Explanation: Discharge is dependent on temperature but minimally.

42. A point in a fluid flow where the flow has come to rest is called __________
a) Pressure point
b) Initial point
c) Flow point
d) Stagnation point
Explanation: Stagnation point is a point at which a flow field of the local velocity of a fluid is equal to zero. At this point, the fluid is brought to rest by the object. When the velocity is zero, the static pressure is maximum.

43. When a fluid is subjected to resistance, it undergoes a volumetric change due to __________
a) Strain
b) Cohesion
d) Compressibility
Explanation: Compressibility is defined as a measure of relative change in volume of a fluid. In fluid mechanics, it is also called as isothermal compressibility due to increase in pressure and temperature.

44. What does Kinematic Viscosity depend upon?
a) Density
b) Pressure
c) Fluid level
d) Fluid Flow
Explanation: Kinematic viscosity is a quantity that represents dynamic viscosity of a fluid per unit density. Density is a major factor that determines the kinematic viscosity. As the temperature increases, density decreases thereby causing changes in the density of the fluid.

45. What is the formula to find the kinematic viscosity of a fluid?
a) Dynamic Viscosity * Temperature
b) Dynamic Viscosity / Density
c) 1/ dynamic viscosity
d) Density / Dynamic Viscosity
Explanation: Density is a major factor that determines the kinematic viscosity. As the temperature increases, density decreases thereby causing changes in the density of the fluid. Thus, kinematic viscosity and density are inversely proportional.

46. A one dimensional flow is also called as __________
b) A flow which involves zero transverse component
c) Uniform Flow
d) Zig-Zag flow
Explanation: One dimensional flow is a flow in which variations of velocity and pressure occur along one space coordinate only. A good example of one dimensional flow is a flow through pipe. During a flow through a pipe, the functions of velocity and pressure occur along the length of the pipe.

47. What is the resultant upward pressure of a fluid on an immersed body called?
a) Buoyancy
b) Metacentre
c) Upthrust
d) Reaction pressure
Explanation: Buoyancy has been explained by Archimedes Principle. The principle states that the force exerted is directly proportional to the pressure difference. This equivalent weight of the body immersed is equal to that of the fluid displaced.

48. If a mass of 1000kg of liquid occupies a volume of one cubic meter, then 1 represents which among the following?
a) Specific Density
b) Specific Weight
c) Specific Gravity
d) Specific Mass
Explanation: Specific Gravity is defined as the ratio of mass or density of a substance to that of the mass or density of a reference substance. But, provided that it has the same volume. It must also have a specified temperature and pressure.

49. At what temperature is the density of water the maximum?
a) 100oC
b) 0oC
c) 5oC
d) 0 K
Explanation: Heating a substance leads to faster movement of molecules due to which density decreases. Whereas, cooling a substance leads to a slower movement of molecules and occupies a smaller volume. Thus, increasing its density.

50. When is a fluid said to be ideal?
a) Non viscous and Incompressible
b) Viscous and compressible
c) Viscous and Incompressible
d) Incompressible
Explanation: Ideal fluids are fluids that have a zero viscosity. This result in a flow called as inviscid flow. Inviscid flow is non viscous and incompressible since there is no existence of shear force due to zero viscosity.

51. If a flow is having the same parameters at any given point, then it is said to be_________
a) Uniform flow
b) Quasi static flow
c) Laminar flow
d) Static flow
Explanation: A flow that takes place at a constant speed without the change in cross section is called a uniform flow. Its parameters remain a constant at any given point.

#### Module-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
Explanation: 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
Explanation: In case of large orifice, velocity always remains variable and hence discharge cannot be calculated.

3. 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
Explanation: The time taken to empty the tank is dependent on Cd as well as depends only on the height and acceleration due to gravity.

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

5. In case of submerged orifice the discharge is substantially dependent on temperature of fluid
a) True
b) False
Explanation: Discharge is dependent on temperature but minimally.

6. A notch is a device used to measure the turbulence of the flowing liquid directly.
a) True
b) False
Explanation: A notch is a device used to measure the flow rate of the flowing liquid, directly.

7. The weir is an attachable structure made up of thermoplastic.
a) True
b) False
Explanation: The weir is a permanent masonry structure made up of concrete.

8. The notch is bigger in size than wier.
a) True
b) False
Explanation: The weir is bigger in size than notch.

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

10. 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
Explanation: There is no such way of classification.

11. The nature of discharge is also a way of classifying notches.
a) True
b) False
Explanation: The nature of discharge is also a way of classifying notches.

12. 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
Explanation: Circular notch is not a way of classifying based on the shape of opening.

13. 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
Explanation: Trapezoidal weir is also called Cipolletti weir.

14. What is not the way of classifying weir based on their shape of crest?
a) Sharp crested weir
c) Narrow crested weir
d) Trapezoidal crested weir
Explanation: Trapezoidal crested weir is not the way of classifying weir based on their shape of crest.

15. 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
Explanation: This is not the way of classifying weir based on the emerging nappe.

16. 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
Explanation: It is the correct parametric definition for ‘large orifice’.

17. In case of any orifice, velocity always remains constant and hence discharge can be calculated.
a) True
b) False
Explanation: In case of large orifice, velocity always remains variable and hence discharge cannot be calculated.

18. 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
Explanation: The time taken to empty the tank is dependent on Cd as well as depends only on the height and acceleration due to gravity.

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

20. In case of submerged orifice the discharge is substantially dependent on temperature of fluid
a) True
b) False
Explanation: Discharge is dependent on temperature but minimally.

21. Find the discharge of water flowing over a rectangular notch of 1.5 m length when the constant head over the notch is 275 mm. Take Cd = .60
a) 400 lit/s
b) 465 lit/s
c) 385 lit/s
d) 575 lit/s
Explanation: Q = 2/3 * L * √2g * H1.5
= .67 * 1.5 * √19.62 * .2751.5
= .385 m3/min.

22. The head of water over a rectangular notch is 900 mm. The discharge is 300 litres/s. Find the length of the notch, when CD =.62
a) .192 m
b) .250 m
c) .205 m
d) .175 m
Explanation: L = 1.5 * Q / (Cd * √2g * H 1.5)
= 1.5 * .3 / (.62 * √19.62 * .91.5)
= .192 m.

23. Find the discharge of water flowing over a rectangular notch of 1.3 m length when the constant head over the notch is 255 mm. Take Cd = .62
a) 400 lit/s
b) 465 lit/s
c) 385 lit/s
d) 575 lit/s
Explanation: Q = 2/3 * L * √2g * H1.5
= .67 * 1.3 * √19.62 * .2551.5
= .385 m3/min.

24. The head of water over a rectangular notch is 700 mm. The discharge is 200 litres/s. Find the length of the notch, when CD =.63
a) .125 m
b) .265 m
c) .250 m
d) .200 m
Explanation: L = 1.5 * Q / (Cd * √2g * H1.5)
= 1.5 * .2 / (.62 * √19.62 * .71.5)
= .125 m.

25. Find the discharge over triangular notch of angle 50° when the head over the V notch
a) .93 m3/min
b) 1.45 m3/min
c) .88 m3/min
d) .90 m3/min
Explanation: Q = 8/15 * √2g * H1.5 * tan(x)
Here, x is the angle.
= 8/15 * √19.62 * .221.5 * tan(50)
= .93 m3/min.

26. The expression for discharge for a right angled notch is more complex than rectangular notch.
a) True
b) False
Explanation: The expression for discharge for a right angled notch is easier than rectangular notch.

27. The results of which are more accurate; rectangular notch or triangular weir.
a) Rectangular notch
b) Triangular weir
c) Both are equally accurate
d) Rectangular weir
Explanation: The results of triangular notch are more accurate for low discharge.

28. What is main reading required in calculation for rectangular notch or weir.
a) H
b) x, x is angle
c) L
d) None of the mentioned
Explanation: H i.e height is main reading required in calculation for rectangular notch or weir.

29. We need to obligatorily have ventilation in triangular notch.
a) True
b) False
Explanation: We need not obligatorily have ventilation in triangular notch.

30. Rectangular notch may or may not have ventilation.
a) True
b) False
Explanation: Rectangular notch must have ventilation.

31. In discharge of water over narrow crested weir, head of water is directly proportional to Discharge Coefficient.
a) True
b) False
Explanation: In discharge of water over narrow crested weir, head of water is inversely proportional to Discharge Coefficient.

32. In discharge of water over narrow crested weir, discharge is directly proportional to the cube root of acceleration due to gravity.
a) True
b) False
Explanation: In discharge of water over narrow crested weir, discharge is directly proportional to the square root of acceleration due to gravity.

33. In discharge of water over ogee weir, discharge is directly proportional to the second power of length.
a) True
b) False
Explanation: In discharge of water over ogee weir, discharge is directly proportional to the first power of length.

34. For discharge over ogee weir discharge is directly proportional to length but for discharge over narrow crested weir it is inversely proportional to length.
a) True
b) False
Explanation: For both weirs it’s same.

35. In discharge of water over narrow crested weir, discharge is directly proportional to the second power of height.
a) True
b) False
Examples: In discharge of water over narrow crested weir, discharge is directly proportional to the one and half power of height.

36. In discharge of water over Ogee weir, discharge is directly proportional to the first power of length.
a) True
b) False
Explanation: This is as per empirical relation.

#### Module-6

1. Which among the following is the formula for continuity equation?
a) ρ(x)V(x)A(x) = Constant
b) A(x) = Constant
c) ρ(x)V(x) = constant
d) P(x)V(x) = constant
Explanation: Continuity equation for a steady one-dimensional flow is ρ(x)V(x)A(x) = Constant. Where ρ = Density of the fluid flow. V = the volume of the fluid flow. And, A = Area of the fluid flow through the cross section of pipe.

2. What is v2/2 in the equation for a control volume in space?
a) Potential energy per unit mass
b) Kinetic energy per unit mass
c) Thermal energy per unit mass
d) Mechanical energy per unit mass
Explanation: According to the first law of thermodynamics, the equation for control volume in space is derived. v2/2 in the equation for a control volume in space is the kinetic energy per unit mass. Therefore, option b is the right choice.

3. Sum of enthalpy and kinetic energy remains a constant in __________
a) Polytropic flow
b) Isentropic flow
d) Mechanical flow
Explanation: The sum of enthalpy and kinetic energy remains a constant in adiabatic flow. It performs a similar role that internal energy performs during a nonflowing system. Thus, the correct option is Adiabatic flow.

4. Eddy viscosity is a turbulent transfer of _________
a) Fluid
b) Heat
c) Momentum
d) Pressure
Explanation: Eddy viscosity is a turbulent transfer of momentum by eddies. It gives rise to an internal fluid friction. It is in analogous to the action of molecular viscosity in laminar fluid flow. Eddy viscosity takes place on a large scale.

5. Which among the following is the equation for Bernoulli?
a) Tds = dh – vdp
b) Tds = dh
c) Tds = dh + vdp
d) Tds = dh/vdp
Explanation: For an adiabatic frictionless flow, the Bernoulli’s equation is identical to its energy equation. The Bernoulli’s equation after integrating changes to Tds = dh – vdp. Thus, the correct option is a.

6. For an isentropic flow ________
a) Enthalpy = 0
b) Entropy = 0
c) Pressure = 0
d) Temperature = 0
Explanation: For an isentropic flow in Tds = dh – vdp, the entropy reduces to zero. That is, the change in entropy value for any isentropic flow (ds)=0. Thus, the correct option is Entropy = 0.

7. Which among the following is Euler’s equation?
a) VdV/dh = 0
b) VdV – dh = 0
c) VdV + dh = 0
d) dh – V = 0
Explanation: The Euler’s equation is given as VdV+dh=0. Where V = volume of the fluid flow and h = enthalpy of the fluid flow. This is identical to the adiabatic form of the energy equation. Thus, the option is VdV + dh = 0.

8. Define Stagnation temperature.
a) The temperature at zero velocity
b) The temperature at zero pressure
c) The temperature at zero heat transfer
d) The temperature at zero volume
Explanation: The stagnation point is the point at which the properties of the fluid are obtained at a local flow where the velocity of the fluid is zero isentropically. Thus, the correct choice for stagnation temperature is ‘a’.

9. What is the viscosity of water at 30oC?
a) 80.1
b) 0.801
c) 801
d) 0.081
Explanation: A graph is plotted with temperature in the x-axis and dynamic viscosity in the y-axis. With the increase in pressure the viscosity decreases. It corresponds to an informal concept of thickness.

11. Speed is of sound is the _________
a) Distance travelled per unit length
b) Distance travelled per unit time
c) Distance travelled per unit pressure
d) Distance travelled per unit temperature
Explanation: The speed of sound is defined as the distance travelled per unit time. It is due to the sound wave. The sound wave propagates through the medium.

12. The sound wave is transmitted through liquids as_________
a) Longitudinal waves
b) Transverse waves
c) Elongated waves
d) Refracted waves
Explanation: The sound wave is transmitted through liquids, gases and plasma as longitudinal waves. It is also called as compressed waves. Longitudinal waves require a medium to propagate. Thus, the correct answer is Longitudinal waves.

13. What are the assumptions made for a fluid flow through a pipe?
a) Fluid inertia is not taken
b) Viscosity is not taken
c) Volume is not considered
d) Mass is not considered
Explanation: During a fluid flow through a pipe, there are various design considerations. But, the two major assumptions are that the flow is assumed to be fully developed. Also, fluid inertia is not taken into account.

14. Which among the following is not generic property of sound?
a) Viscosity
b) Amplitude
c) Direction
d) Frequency
Explanation: Viscosity is not a generic property sound. It is defined as the property of resistance to flow of fluid. Resistance to flow of fluid takes place when one layer of fluid slides over the other. Viscosity is not a generic property.

15. Sound perceptible by humans has frequencies from _______
a) 20 to 2000 Hz
b) 20 to 20000 Hz
c) 10 to 10000 Hz
d) 30 to 30000 Hz
Explanation: Sounds that are audible to a human ear ranges from 20 to 20000 Hz. At standard temperature and pressure of air, the corresponding wavelengths of sound range from 17m to 17mm.

16. What is the speed of sound in dry air?
a) 331.2 m/s
b) 300 m/s
c) 250 m/s
d) 230 m/s
Explanation: The speed of sound in dry air at a temperature of zero degrees Celsius is equal to 331.2 m/s. Speed of sound in air is denoted by the symbol ‘c’. Thus the correct answer for the following is 331.2 m/s.

17. What is the speed of sound at 20oC?
a) 331.2 m/s
b) 350 m/s
c) 343 m/s
d) 300 m/s
Explanation: The speed of sound in dry air at a temperature of 20oC is equal to 343 m/s. It is found out using the relation of kilometre and miles. One kilometre = 2.91 seconds, and one mile = 4.69 seconds.

18. Speed of sound in an ideal gas depends on _______
a) Temperature and pressure
b) Surface area and volume
c) Temperature and composition
d) Composition and surface area
Explanation: Speed of sound in ideal gas depends on its composition and temperature. The speed of sound has a weak dependence on frequency and pressure. As there is a slight deviating behaviour in an ideal fluid.

19. Transverse wave is also called as ________
a) Shear wave
b) Compression wave
c) Compressed wave
d) Longitudinal wave
Explanation: Transverse wave is also called as a shear wave. Transverse wave or shear waves occur only in solids. It occurs only in solids because only solids support elastic deformations. It is also called as an elastic wave.

20. Which among the following determines the geometric orientation of transverse waves?
a) Dichroism
b) Optical activity
c) Polarization
d) Photon spin
Explanation: Polarization is defined as a property applied to transverse waves or shear waves. The main function of polarization is to determine the geometric orientation of transverse waves or shear waves.

21. The exit velocity in the nozzle increases as per __________
a) Stagnation point
b) Continuity equation
c) Prandtl Number
d) Newton’s law
Explanation: In the nozzle, the exit velocity of the fluid increases as per the continuity equation. Continuity equation is given as Av= constant as per the Bernoulli’s equation. It is essential for an incompressible flow.

22. With the increase in pressure, the exit velocity _________
a) Decreases
b) Increases
c) Same
d) Independent
Explanation: Pressure is inversely proportional to the velocity. So, with the increase in pressure, the exit velocity decreases. We know that the pressure is equal to force per unit area, this contradicts the above statement.

23. The Prandtl Number approximates ___________
a) Momentum diffusivity to thermal diffusivity
b) Thermal diffusivity to momentum diffusivity
c) Shear stress to thermal diffusivity
d) Thermal diffusivity to kinematic viscosity
Explanation: The Prandtl number is a dimensionless number. It approximates the ratio of momentum diffusivity to thermal diffusivity. It can be expressed as Pr = v/ α(1). Where α= thermal diffusivity and v= momentum diffusivity.

24. Pumps increase __________
a) Pressure
b) Velocity
c) Momentum
d) Heat
Explanation: Pumps increase pressure rather than velocity. During the pumping process, a housing is provided for the pumping elements. These parts can change the speed. Pumps create a passage way that will squirt the fluid passing through it. Thus, pumping increases pressure.

25. Which among the following is the formula for volumetric flow rate?
a) Q = v/A
b) Q = Av
c) Q = A+v
d) Q = A-v
Explanation: Volumetric flow rate is given by Q= A.v. Where v is the flow velocity of the fluid, and A is the area of cross section of the surface. Area of a surface is also called as the vector area. Thus, the right answer is Q = Av.

26. Which among the following is the formula for mass flow rate?
a) Q = m/p
b) Q = mp
c) Q = m + p
d) Q = m – p
Explanation: Mass flow rate is given by Q=m/p. This is a relation expressed for mass flow rate. When ‘m’ is the mass flow rate. And, p is the density of the fluid flow. They are expressed in their standard units.

27. Compressible flow is a flow that deals with ______
a) Fluid temperature
b) Fluid pressure
c) Fluid density
d) Fluid geometry
Explanation: Compressible flow is a branch of fluid mechanics that deals with different types of flow. Its main significance lies in the change in fluid density. Thus, the correct option is Fluid density .

28. Compressible flow mainly deals with _______
a) Solid dynamics
b) Liquid dynamics
c) Gas dynamics
d) Solid and liquid dynamics
Explanation: Compressible flow is a branch of fluid mechanics that deals with different types of flow. Its main significance lies in the change in fluid density. It deals with gas dynamics.

29. Which among the following is an assumption of the compressible flow?
a) Resistance to flow of object
b) No-slip condition
c) Known mass flow rate
d) Resistance to flow of heat
Explanation: The related assumption of a compressible fluid flow is No-slip condition. It is assumed that the flow velocity at the solid surface is equal to the velocity of the surface itself. It is in direct consequence with the continuum flow.

30. What is Mach number?
a) Speed of object * speed of sound
b) Speed of object /speed of sound
c) Speed of object + speed of sound
d) Speed of object- speed of sound
Explanation: Mach number is defined as the ratio of the speed of an object to the speed of sound. Mach number is denoted by ‘M’. Mach number ranges from zero to infinity. It falls into several flow regimes.

31. What is the Mach number at room temperature?
a) 310 m/s
b) 320 m/s
c) 330 m/s
d) 340 m/s
Explanation: Mach number is defined as the ratio of the speed of an object to the speed of sound. Mach number is denoted by ‘M’. Mach number ranges from zero to infinity. It falls into several flow regimes. It is 340 m/s at room temperature.

32. In a one-dimensional flow, the gas flows through one spatial dimension, namely its length.
a) True
b) False
Explanation: One dimensional flow refers to the flow of gas through a duct or channel in which the flow parameters are assumed to change significantly along a particular dimension. In this case, it’s about its duct length.

33. The compressible flow is assumed to be _____________
a) Isentropic
c) Polytropic
Explanation: Compressible flow is a branch of fluid mechanics that deals with different types of flow. Its main significance lies on the change in fluid density. It deals with gas dynamics. Flow is assumed to be isentropic.

34. Ratio of duct length to width length in a compressible flow is_______
a) More than 5
b) Less than 5
c) More than or equal to 5
d) Less than or equal to 5
Explanation: In a compressible flow, the flow is usually in a single dimension. One dimensional flow refers to the flow of gas through a duct or channel in which the flow parameters are assumed to change significantly. Thus, it is less than or equal to 5.

35. The fluid speed through the nozzle is altered with________
a) Acceleration
b) Deceleration
c) Constant speed
d) Zero
Explanation: The fluid speed through the nozzle is altered as the speed accelerates from subsonic speed to supersonic speed in a regime. It alters a nozzle and a diffuser.

36. What happens to velocity in the converging duct?
a) Increases
b) Decreases
c) Same
d) Independent
Explanation: Mass flow rate is given by Q = m/p. This is a relation expressed for mass flow rate. With the presence of a converging duct, the velocity increases. At this point, the area of the duct is less than zero.

37. What happens to velocity in the diverging duct?
a) Increases
b) Decreases
c) Same
d) Independent
Explanation: Mass flow rate is given by Q = m/p. This is a relation expressed for mass flow rate. With the presence of a converging duct, the velocity decreases. At this point, the area of the duct is more than zero.

38. The area of the duct is either maximum or minimum when the_________
a) Mach number = 1
b) Mach > 1
c) Mach = 0
d) Mach < 0
Explanation: Mass flow rate is given by Q = m/p. This is a relation expressed for mass flow rate. The area of the duct is either maximum or minimum when the Mach number of the fluid flow is exactly one.

39. Which among the following is an assumption of the compressible flow?
a) Resistance to flow of object
b) No-slip condition
c) Known mass flow rate
d) Resistance to flow of heat
Explanation: The related assumption of a compressible fluid flow is No-slip condition. It is assumed that the flow velocity at the solid surface is equal to the velocity of the surface itself. It is in direct consequence of the continuum flow.

40. Which among the following is an example of a converging-diverging nozzle?
a) De Laval nozzle
b) High velocity nozzle
c) Magnetic nozzle
d) Vacuum nozzle
Explanation: De-Laval nozzle is an example of a converging diverging nozzle. It a tube that is pinched in the mid marking with a particular balance. It is used to accelerate, hot pressurized gases that pass through a higher supersonic speed in the axial thrust.

41. __________ is referred as the temperature at a stagnation point in the flow of fluids in fluid mechanics and thermodynamics.
a) Absolute temperature
b) Maximum temperature
c) Stagnation temperature
d) Hydraulic temperature
Explanation: Stagnation temperature is the temperature at the stagnation point of the flow of fluids. In thermodynamics and fluid mechanics, these terms find application. At a stagnation point the speed of the fluid is zero and all of the kinetic energy has been converted to internal energy and is added to the local static enthalpy.

42. In ________ and _______ kind of flow, the stagnation temperature is equal to the total temperature
a) compressible, incompressible
b) stagnated, non-stagnated
c) dynamic, non-dynamic
d) turbulent, passive
Explanation: In compressible and incompressible kind of flow, the stagnation temperature is equal to the total temperature. This occurs at all points on the streamline. Eventually, this leads to the stagnation point.

43. _____ is the law employed in the derivation of stagnation point.
a) Hooke’s law
b) Poisson’s law
c) Second law of thermodynamics
d) First law of thermodynamics
Explanation: First law of thermodynamics is the law employed in the derivation of stagnation point. It states that the change in the internal energy ΔU of a closed system is equal to the amount of heat Q supplied to the system, subtracting the amount of work W done by the system on its surroundings. It is a modified form of the law of conservation of energy.

44. A bimetallic ________ is generally utilized to measure stagnation temperature
a) Transistor
b) Thermometer
c) Diode
d) Thermocouple
Explanation: A bimetallic thermocouple is generally utilized to measure stagnation temperature. However, there must be allowances for thermal radiation. This is done in order to avoid the occurrence of errors.

45. Stagnation point is the point in fluid mechanics where the velocity of the fluid at that point is _____
a) zero
b) infinite
c) constant
d) unity
Explanation: Stagnation point is the point in fluid mechanics where the velocity of the fluid at that point is zero. Stagnation points occur at places where the fluid is brought to a state of rest by an object. They usually exist at the surface of objects.

46. _________ proves that the static pressure is maximum when the velocity is zero
a) Laws of Thermodynamics
b) Bernoulli’s Equation
c) Hooke’s law
d) Principle of continuity
Explanation: Bernoulli’s equation proves that the static pressure is maximum when the velocity is zero. Bernoulli’s principle states that a rise in the speed of a fluid occurs simultaneously with a drop in pressure or a drop in the fluid’s potential energy. It is named after Daniel Bernoulli, who stated it.

47. Total pressure is an addition of static pressure and ______
a) Dynamic pressure
b) Stagnation pressure
c) Fluid pressure
d) Instantaneous pressure
Explanation: Total pressure is an addition of static pressure and dynamic pressure. In incompressible flow, the stagnation pressure is equal to the sum of dynamic pressure and static pressure. So here, stagnation pressure is equal to total pressure.

48. The pressure coefficient at a stagnation point is _____
a) +1
b) -1
c) 0
d) Infinite
Explanation: The pressure coefficient at a stagnation point is unity. This is referred to as +1. A pressure coefficient is a dimensionless number which describes the relative pressures throughout a flow field in fluid dynamics.

49. _________ minus freestream static pressure gives freestream dynamic pressure
a) Stagnation pressure
b) Total pressure
c) Fluid pressure
d) Instantaneous pressure
Explanation: Stagnation pressure minus freestream static pressure gives freestream dynamic pressure. This plays an important role in determining the pressure coefficient. Hence, the pressure coefficient at stagnation points is +1.

50. On a streamlined body fully immersed in a potential flow, there are ____ stagnation points
a) 1
b) 2
c) 0
d) Infinite