1. For a fully-developed pipe flow, how does the pressure vary with the length of the pipe?
a) Linearly
b) Parabolic
c) Exponential
d) Constant
Answer: a
Explanation: In a zero acceleration fully-developed flow in a pipe, the pressure gradually decreases linearly along the length of the pipe. Hence, the pressure variation is said to be linear.

2. When a problem states “The velocity of the water flow in a pipe is 20 m/s”, which of the following velocities is it talking about?
a) RMS velocity
b) Average velocity
c) Absolute velocity
d) Relative velocity
Answer: b
Explanation: In a pipe-flow, the velocity is always referred to the average velocity. There may be a case where all water particles move in the same direction with 20 m/s, then the average velocity will be equal to absolute velocity. But, this is only a special case. Hence, average velocity will always be true.

3. Which of the factors primarily decide whether the flow in a circular pipe is laminar or turbulent?
a) The Prandtl Number
b) The Pressure gradient along the length of the pipe
c) The dynamic viscosity coefficient
d) The Reynolds Number
Answer: d
Explanation: High Reynolds number flows (> 4000) are turbulent flows, whereas low Reynolds number flows (< 2100) are laminar flows. The viscosity coefficient is a part of the Reynolds number, but isn’t the only criteria for decision.

4. How is Reynolds number defined as?
a) Ratio of pressures in the inlet to the outlet of a pipe
b) The product of velocity of the flow and the diameter of the pipe, divided by the kinematic viscosity of fluid
c) The product of density of the fluid, velocity of the flow and the diameter of the pipe, divided by the dynamic viscosity of fluid
d) Ratio of inertia force to viscous force
Answer: d
Explanation: The question demands the definition and not the commonly used formula of Reynolds number. Some of them denote the formula of Reynolds number. The definition of Reynolds number is the ratio of inertia force to viscous force in a pipe flow.

5. A circular pipe of a radius of 7 cm is used for water flow transmission. This pipe is moulded into another pipe with a square cross-section keeping the length same. (Ignore the thickness of the pipe). Calculate the hydraulic diameter of the moulded pipe. (Take π = 22/7).
a) 11 cm
b) 7 cm
c) 3.5 cm
d) 22 cm
Answer: a
Explanation: The perimeter of the circular cross section and the square cross section will remain the same. Perimeter = 44 cm. Side of square = 11 cm. Hydraulic diameter DH of the pipe is given by 4A/P, where A = Area of cross section and P = wetted perimeter. In case of a square DH = side. Hence, the hydraulic diameter is 11 cm.

6. Water flows through a circular tube with a velocity of 2 m/s. The diameter of the pipe is 14 cm. Take kinematic viscosity of water 10-6 m2/s and density of water 1000 kg/m3.
a) 2.8*108
b) 2.8*105
c) 2800
d) 28000
Answer: b
Explanation: Reynolds number is given by VD/ν = (2*0.14)/10-6. Density given is extra information. One shouldn’t be confused by that.

7. The Reynolds number is found out for a flow in a circular pipe. This circular pipe is moulded into a square pipe, keeping length of the pipe same. Ignore the thickness of the pipe. The Reynolds number changes by __________
a) 57% decrease
b) 57% increase
c) 43% decrease
d) 43% increase
Answer: b
Explanation: The Reynolds number directly depends upon the hydraulic diameter of the pipe. Suppose the diameter of the pipe is D, the hydraulic diameter of square pipe is 1.57D. Hence, 57% increase.

8. The flow through a circular pipe is laminar. Now, the fluid through the pipe is replaced with a more viscous fluid and passed through the pipe again with the same velocity. What can we say about the nature of this flow?
a) The flow will become turbulent
b) The flow will be a transition flow
c) The flow will remain laminar
d) The Reynolds number of the earlier flow is required to answer this question
Answer: c
Explanation: A flow through a circular pipe is said to be laminar when the Reynolds number is below 2100. A more viscous fluid would have a higher velocity coefficient, thus reducing the Reynolds number further at the same conditions. Hence, the Reynolds number will be well below 2100. Flow will remain laminar.

9. What can be the maximum diameter of the pipe for the water flow of velocity 1 m/s (ν = 10-6) to be laminar in nature? Assume Lower critical Reynolds number to be 2100.
a) 2.1 mm
b) 21 mm
c) 21 cm
d) 0.21 mm
Answer: a
Explanation: If the Reynolds number of the flow is below its lower critical Reynolds number, the flow is clearly laminar. The maximum diameter can be found for Re = 2100. The diameter comes out to be 2.1 mm.

10. Which of the following flows have the highest critical Reynolds number (lower)?
a) Flow in a pipe
b) Flow between parallel plates
c) Flow in an open channel
d) Flow around the spherical body
Answer: a
Explanation: The approximate lower critical Reynolds number for Flow in a pipe, flow between parallel plates, flow in an open channel and flow around the spherical body are 2000, 1000, 500 and 1 respectively. Hence, the maximum is for internal pipe flow.

1. What is the unit of shear stress?
a) N/m3
b) N/mm3
c) N/m
d) Pascal
Answer: d
Explanation: Shear stress is defined as the force acting per unit area. Thus, the unit of shear stress is equal to N/m2. Since, 1 Pa =1 N/m2, Pascal is the most suitable one.

2. Shear stress is caused due to _______
a) Friction
b) Temperature
c) Pressure
d) Volume
Answer: a
Explanation: Shear stress is caused due to friction between fluid particles. It is formed due to the presence of fluid viscosity. Shear stress arises from the force vector component which is parallel to the cross section.

3. Which among the following is a formula for shear stress?
a) τ = F*A
b) τ = F/A
c) τ = F/m
d) τ = F*m
Answer: b
Explanation: Shear stress is defined as the force acting per unit area. Shear stresses arise from shear components(forces), which are pairs of equal and opposite forces. These forces act on the opposite side of the object.

4. Which among the following is the correct formula to find out the shear modulus(G)?
a) E/2
b) v/2
c) E/2(1+v)
d) 2E(1+v)
Answer: c
Explanation: Shear modulus is also called as modulus of rigidity. It is defined as the ratio of shear stress to shear strain. Since Young modulus is equal to stress by strain. The most suitable option is option c. (E= Young’s Modulus, v= poison’s ratio)

5. Which among the following is an assumption of Hagen-Poiseuille equation?
a) Fluid is compressible
b) Fluid is uniform
c) Fluid is laminar
d) Fluid is turbulent
Answer: c
Explanation: Fluid flow is laminar as it is assumed to be incompressible and Newtonian. The flow is laminar through the pipe of constant cross section. Thus, there is no acceleration of fluid in the pipe. Therefore, Hagen-Poiseuille assumed that fluid flow is laminar.

6. What is the unit of pressure gradient?
a) Pa/m
b) Nm
c) Pa
d) N/m
Answer: a
Explanation: Pressure gradient is a dimensional quantity. It is expressed in units of pressure per unit length. It determines which quantity and which direction the pressure changes around a particular location.

7. Which of the following is not a basic type of stress?
a) Volumetric stress
b) Shear stress
c) Compressive stress
d) Tensile stress
Answer: a
Explanation: Volumetric stress is not a basic classification among the type of stresses as it describes the tendency of an object to deform in all directions. It deforms when the load acts uniformly in all directions.

8. What type of force does stress produce?
a) Radial force
b) External force
c) Internal resistive force
d) Axial force
Answer: c
Explanation: According to the continuum mechanics, stress is a physical quantity that produces internal forces. For example: When a solid bar supports a weight, each particle of the bar pushes the particles immediately below it. This happens due to the internal resistive force that is developed due to the stress on the body.

9. Hooke’s law is applicable within what limit?
a) Fracture point
b) Elastic limit
c) Ultimate strength
d) Plastic limit
Answer: b
Explanation: Hooke’s law states that force is directly proportional to its extension. Hooke’s law is applicable within the elastic limit, when the body is deformed. Example: plucking the strings of a guitar.

10. Define Factor of safety
a) Ultimate stress/Permissible stress
b) Ultimate stress/ Shear stress
c) Compressive stress/ Ultimate stress
d) Tensile stress/Shear stress
Answer: a
Explanation: Factor of safety determines the maximum load carrying capacity. It tells us how much stronger the system is than it usually needs to be for a particular specified load. It is the ratio of allowable stress to the actual stress.

11. What is an aspect ratio in universal velocity distribution?
a) b*h
b) b/h
c) b+h
d) b-h
Answer: b
Explanation: Aspect ratio in universal velocity ratio is defined as the ratio of free surface of the fluid flow width to the depth of water. The formula is : Aspect ratio= b/h. It can also be defined as the ratio of span to the mean chord in an aero foil.

12. What is the ratio of maximum velocity to the average velocity when the fluid passes through two parallel plates?
a) 1/4
b) 1/2
c) 3/4
d) 1
Answer: c
Explanation: The maximum velocity occurs at the centre. At the centre, the radius is equal to zero. The average velocity is obtained by dividing the discharge of fluid. The discharge takes place across the cross-sectional area of the pipe.

13. 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
Answer: a
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.

14. Eddy viscosity is a turbulent transfer of_________
a) Fluid
b) Heat
c) Momentum
d) Pressure
Answer: c
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 a laminar fluid flow. Eddy viscosity takes place on a large scale.

15. What is the function of transilient turbulence theory?
a) Parameterizing turbulence
b) Stopping turbulence
c) Initiating turbulence
d) Detecting turbulence
Answer: a
Explanation: Transilient turbulence theory is the method used for parameterizing turbulence. Its main function is to allow all non-local vertical mixing between every pair of grid points. It happens in mainly in the vertical column.

16. What is the formula for kinematic eddy viscosity?
a) Eddy viscosity / kinematic viscosity
b) Eddy viscosity * kinematic viscosity
c) Eddy viscosity / mass density
d) Eddy viscosity / dynamic viscosity
Answer: c
Explanation: Kinematic eddy viscosity is defined as the ratio between Eddy viscosity and mass density of the fluid. It happens mainly at one hundred times the molecular kinematic viscosity. It is in the order 1m2s-1.

17. Eddy diffusion happens due to_________
a) Eddy motion
b) Fluid motion
c) Water constraint
d) Eddy constraint
Answer: a
Explanation: Eddy diffusion happens due to Eddy motion. This eddy motion is created due to fluid mixing. The fluid mixture causes the formation of eddies. Eddies can vary in size from small microscales to subtropical scales.

18. When is the fluid called laminar?
a) Reynolds number is greater than 2000
b) Reynolds number is less than 2000
c) The density of the fluid is high
d) Low viscosity
Answer: b
Explanation: Reynolds number is a dimensionless quantity. It helps to predict the flow pattern in fluid mechanics. At low Reynolds number, the flow has a very low density, due to which the value of Reynolds number is less than 2000.

19. When is a fluid called turbulent?
a) Reynolds number is greater than 2000
b) Reynolds number is less than 2000
c) The density of the fluid is low
d) High viscosity of fluid
Answer: a
Explanation: Reynolds number is a dimensionless quantity. It helps to predict the flow pattern in fluid mechanics. At high Reynolds number, the flow has a very high density, due to which the value of Reynolds number is greater than 2000.

20. Coefficient of friction of a laminar flow is_________
a) Re/16
b) Re/64
c) 16/Re
d) 64/Re
Answer: c
Explanation: Coefficient of friction is defined as the value that shows relationship between force and the normal reaction. It is mainly used to find out an object’s normal force and frictional force. Thus, it is equal to 16/Re.

1. What is the dimension for drag coefficient?
a) Newton/s
b) m/s
c) kg/N
d) Dimensionless
Answer: d
Explanation: In fluid dynamics, the drag coefficient has no dimensions. It is a dimensionless quantity. Drag coefficient is used to quantify the resistance of an object in a fluid environment. It is mainly used in air and water.

2. Skin friction acts on the component of _________
a) Profile drag
b) Surface blade
c) Vane angles
d) Parallel movement
Answer: a
Explanation: Skin friction acts on the component of profile drag. Pressure drag is also called as form drag. It mainly arises because of the shape of the object. Thus, the correct answer is profile drag.

3. Bodies with a larger cross-section will have________
a) Lower drag
b) Higher drag
c) Same drag
d) No drag
Answer: b
Explanation: Bodies with a larger cross-section will have higher drag. Pressure drag is also called as form drag. It mainly arises because of the shape of the object. Thus, the correct option ‘b’.

4. Drag coefficient is denotes as_______
a) Cd
b) Bc
c) Dc
d) Tc
Answer: a
Explanation: In fluid dynamics, the drag coefficient has no dimensions. It is a dimensionless quantity. Drag coefficient is used to quantify the resistance of an object in a fluid environment. It is mainly used in air and water. It is denoted as Cd.

5. The drag coefficient of a complete structure such as an aircraft includes________
a) Form drag
b) Pressure drag
c) Interference drag
d) Induced drag
Answer: c
Explanation: The drag coefficient of a complete structure such as an aircraft includes interference drag. It results when an airflow around one part of an object. The two airflows must speed up in order to pass through the restricted area.

6. The drag coefficient is directly proportional to the ___________
a) Drag force
b) Mass density
c) Area
d) Flow speed
Answer: a
Explanation: The drag coefficient is directly proportional to the drag force. In fluid dynamics, the drag coefficient has no dimensions. It is a dimensionless quantity. Drag coefficient is used to quantify the resistance of an object in a fluid environment.

7. If the friction is neglected, then_______
a) Vr1 > Vr2
b) Vr1 < Vr2
c) Vr1 = Vr2
d) Vr1 is a zero
Answer: c
Explanation: The relative velocity of the jet is denoted as Vr1. It is the relative velocity at the inlet to the vane. Relative velocity of inlet to the vane is obtained by subtracting vectorially the velocity of the vane with its absolute velocity. It happens in the same way for Vr2. Thus, If the friction is neglected, then Vr1= Vr2.

8. Drag force is directly proportional to ________
a) Density of fluid
b) Mass density
c) Area
d) Flow speed
Answer: a
Explanation: Drag force is directly proportional to density of the fluid. It is the force that acts opposite to the relative motion of any object moving with respect to its surroundings. Thus, the correct option is ‘a’.

9. Drag force can exist between two layers of liquid.
a) True
b) False
Answer: a
Explanation: Drag force can exist between two layers of liquid. They can even exist in between two layers of solid surface. Unlike other resistive forces, they are dependent on velocity.

10. Drag coefficient is a function of _________
a) Mach number
b) Froude’s number
c) Laminar flow
d) Reynolds number
Answer: a
Explanation: Drag coefficient is a function of Mach number. In fluid dynamics, the drag coefficient has no dimensions. It is a dimensionless quantity. Drag coefficient is used to quantify the resistance of an object in a fluid environment.

11. For a streamlined body to achieve low drag coefficient, the boundary layer must_________
a) Flow over the body
b) Be attached to the body
c) Move away from the body
d) Move parallel to the body
Answer: b
Explanation: For a streamlined body to achieve low drag coefficient, the boundary layer must be attached to the surface of the body for a long time as possible. This causes the wake to be narrow.

12. There will be a transition from laminar flow to turbulent flow when______
a) Reynolds number increases
b) Reynolds number decreases
c) Reynolds number is the same
d) Froude’s number increases
Answer: a
Explanation: There will be a transition from laminar flow to turbulent flow with the increase in the Reynolds number. Reynolds number below 2000 is laminar flow and Reynolds number above 2000 is for turbulent flow.

13. With the increase in flow velocity, Reynolds number_________
a) Increases
b) Decreases
c) Same
d) Independent
Answer: a
Explanation: With the increase in flow velocity, Reynolds number increases. Reynolds number below 2000 is laminar flow and Reynolds number above 2000 is for turbulent flow. Thus, the correct option is Increases.

14. With the decrease in the viscosity, Reynolds number ________
a) Increases
b) Decreases
c) Same
d) Independent
Answer: a
Explanation: With the decrease in viscosity, Reynolds number increases. Reynolds number below 2000 is laminar flow and Reynolds number above 2000 is for turbulent flow. Thus, the correct option is Increases.

15. How can we determine whether the flow is laminar or turbulent?
a) Reynold’s number
b) Mach number
c) Froude number
d) Knudsen number
Answer: a
Explanation: Reynold’s number is used to determine whether the flow is laminar or turbulent. If Reynold’s number is less than 2000, it is a laminar flow. If Reynold’s number is greater than 2000, then it is a turbulent flow.

16. The flow separation occurs when the fluid travels away from the __________
a) Surface
b) Fluid body
c) Adverse pressure gradient
d) Inter-molecular spaces
Answer: c
Explanation: Adverse pressure gradient takes place when the static pressure increases. It increases the direction of the flow. Adverse pressure gradient plays an important role in flow separation. Thus, option c is correct.

17. The swirl caused due to eddies are called as ______
a) Vortices
b) Vertices
c) Volume
d) Velocity
Answer: a
Explanation: Vortices are a region in a fluid. It takes place when the flow revolves around an axis line. Vortices can be straight or curved. They form shapes like smoke rings and whirlpools.

18. Eddy viscosity is a turbulent transfer of_________
a) Fluid
b) Heat
c) Momentum
d) Pressure
Answer: c
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.

19. Which among the following is a device that converts a laminar flow into a turbulent flow?
a) Dead Weight Gauge
b) Vacuum Gauge
c) Turbulator
d) Ionization Gauge
Answer: c
Explanation: Turbulator is a device that converts a laminar flow into a turbulent flow. The turbulent flow can be desired parts of an aircraft or also in industrial applications. Turbulator is derived from the word “turbulent”.

20. Boundary layer separation does not undergo detachment.
a) True
b) False
Answer: b
Explanation: Boundary layer separation undergoes detachment from the surface into a broader wake. It occurs mainly when the portion of the boundary layer is closest to the wall. It leads to reverse in the flow direction.

21. With the boundary layer separation, displacement thickness________
a) Increases
b) Decreases
c) Remains Same
d) Independent
Answer: a
Explanation: With the boundary layer separation, displacement thickness increases sharply. This helps to modify the outside potential flow and its pressure field. Thus, option ‘a’ is the correct choice.

22. 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
Answer: d
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.

23. What is D’Alembert’s Paradox?
a) Resistance= 0
b) Drag force= 0
c) Temperature = 0
d) Pressure gradient= 0
Answer: b
Explanation: D’Alembert’s Paradox states that for an incompressible and inviscid flow potential flow, the drag force is equal to zero. The fluid is moving at a constant velocity with respect to its relative fluid.

24. The steady-state flow must satisfy ___________
a) Kirchhoff’s law
b) Newtons law
c) Rutherford’s experiment
d) Kepler’s law
Answer: a
Explanation: The steady state flow must satisfy Kirchhoff’s first and second law. The first law states that the total flow into the junction equals the total flow away from the junction. Second law is called as the law of conservation of mass. It states that between two junctions, the head loss is independent of the path followed.

25. The main property that affects a boundary layer is__________
a) Temperature
b) Pressure
c) Viscosity
d) Surface tension
Answer: c
Explanation: A boundary layer is an important concept that refers to the layer of fluid. The fluid that is in the immediate vicinity of a bounding surface. The main property that affects a boundary layer is viscosity.

26. The layer that is influenced by a planetary boundary is called______
a) Atmospheric boundary layer
b) Lithosphere
c) Troposphere
d) Hydrosphere
Answer: a
Explanation: The planetary boundary layer is also called as atmospheric boundary layer(ABL). It is the lowest part of the atmosphere. The behaviour of ABL is directly influenced by its contact with the planetary surface.

27. What is the other name for Stoke’s boundary layer?
a) Momentum boundary layer
b) Atmospheric boundary layer
c) Oscillatory boundary layer
d) Thermal boundary layer
Answer: c
Explanation: Stoke’s boundary layer is also called as Oscillatory boundary layer. It is a boundary layer that is close to a solid wall. It moves in an oscillatory motion. It arrested by a viscous force acting in the opposite direction.

28. Eddy viscosity is a turbulent transfer of_________
a) Fluid
b) Heat
c) Momentum
d) Pressure
Answer: c
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.

29. The laminar boundary layer is a _________
a) Smooth flow
b) Rough flow
c) Uniform flow
d) Random flow
Answer: a
Explanation: For a laminar boundary layer the fluid moves in a very smooth flow. The laminar flow creates less skin friction drag. It is a less stable flow. The laminar boundary layer has got an increase in its thickness.

30. The turbulent boundary layer is a _________
a) Non-uniform with swirls
b) Uniform
c) Less stable
d) Smooth
Answer: a
Explanation: For a turbulent boundary layer the fluid moves in different direction producing swirls. It has more skin friction drag than that of laminar boundary layer. It is more stable when compared to laminar.

31. How do we measure the flow rate of liquid?
a) Coriolis method
b) Dead weight method
c) Conveyor method
d) Ionization method
Answer: a
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.

32. How does a turbulent boundary layer produce swirls?
a) Due to random motion
b) Collision of molecules
c) Due to eddies
d) Due to non-uniform cross section
Answer: c
Explanation: For a turbulent boundary layer the fluid moves in different direction producing swirls. It produces swirls due to the presence of eddies. The smooth laminar boundary layer flow breaks down and transforms to a turbulent flow.

33. Define Viscosity.
a) Resistance to flow of object
b) Resistance to flow of air
c) Resistance to flow of fluid
d) Resistance to flow of heat
Answer: c
Explanation: Viscosity is developed due to the relative motion between two surfaces of fluids at different velocities. It happens due to the shear stress developed on the surface of the fluid.

1. 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
Answer: d
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.

2. When a fluid is subjected to resistance, it undergoes a volumetric change due to __________
a) Strain
b) Cohesion
c) Adhesion
d) Compressibility
Answer: d
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.

3. What does Kinematic Viscosity depend upon?
a) Density
b) Pressure
c) Fluid level
d) Fluid Flow
Answer: a
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.

4. 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
Answer: b
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.

5. A one dimensional flow is also called as __________
a) A steady flow
b) A flow which involves zero transverse component
c) Uniform Flow
d) Zig-Zag flow
Answer: b
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.

6. What is the resultant upward pressure of a fluid on an immersed body called?
a) Buoyancy
b) Metacentre
c) Upthrust
d) Reaction pressure
Answer: a
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.

7. 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
Answer: c
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.

8. At what temperature is the density of water the maximum?
a) 100oC
b) 0oC
c) 5oC
d) 0 K
Answer: c
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.

9. When is a fluid said to be ideal?
a) Non viscous and Incompressible
b) Viscous and compressible
c) Viscous and Incompressible
d) Incompressible
Answer: a
Explanation: Ideal fluids are fluids that have 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.

10. 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
Answer: a
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.

11. The best place to place a pitot tube on an aircraft for velocity measurement is just behind the jet engine.
a) True
b) False
Answer: b
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.

12. 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
Answer: c
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.

13. 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
Answer: d
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.

14. The Bernoulli’s equation in fluid dynamics is valid for _________
a) Compressible flows
b) Transient flows
c) Continuous flows
d) Viscous flows
Answer: c
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.

15. 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
Answer: a
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.

16. 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
Answer: b
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.

17. 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
Answer: d
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.

18. 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
Answer: a
Explanation: Even though a pitot tube may be primarily used to find the 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.

19. When a cricket bat hits a cricket ball, the impulse is applied on the_________
a) Bat
b) Ball
c) Bat and ball
d) No impulse is applied
Answer: b
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
Answer: b
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
Answer: a
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
Answer: c
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
Answer: a
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 the momentum of an object is equal to the_______
a) Internal Energy
b) Entropy
c) Impulse
d) Enthalpy
Answer: c
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. What is the unit of specific impulse?
a) m/s
b) m2/s
c) m3/s
d) m/s2
Answer: a
Explanation: Specific impulse is equal to the exhaust velocity of the fluid. Since, the unit of exhaust velocity is m/s, the unit of specific impulse is also the same. It is used to measure the efficacy of rocket propellants.

26. What is the formula to find specific impulse?
a) Jsp=m/v
b) Jsp= J/m
c) Jsp=T/m
d) Jsp=J/q
Answer: b
Explanation: Specific impulse is defined as impulse per weight. It can also be defined as thrust per weight of a flow rate. It is equal to the exhaust velocity divided by acceleration due to gravity. (SI Unit: m/s)

27. Angular momentum is a _______ quantity
a) Scalar
b) Vector
c) Infinite
d) Finite
Answer: b
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.

28. 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
Answer: a
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.

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

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

31. 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
Answer: c
Explanation: None.

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

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

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

35. 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
Answer: b
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.

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

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

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

1. What is the mathematical technique used to predict physical parameters?
a) Combustion analysis
b) Pressure analysis
c) Dimensional analysis
d) Temperature analysis
Answer: c
Explanation: Dimensional analysis is a process which is used to determine physical parameters that influence the fluid flow. The analysis is based on the fundamental units. The fundamental units are mass, length and time.

2. Which among the following method is used to find a functional relationship with respect to a parameter?
a) Rayleigh’s method
b) Rutherford’s method
c) Newton’s laws
d) Doppler effect
Answer: a
Explanation: Rayleigh’s method is a basic method for finding the functional relationship. The functional relationship is found with respect to a physical parameter. It is illustrated using the MLT system.

3. Which among the following is not the correct symbol?
a) Size- l
b) Velocity – v
c) Gravity – g
d) Viscosity – a
Answer: d
Explanation: The symbol used for viscosity is false. Viscosity is denoted by the symbol ‘µ’ (Mew). It is defined as the resistance to flow of fluid. Resistance takes place as one layer of fluid slides over the other.

4. Which among the following is the correct format for Rayleigh’s method?
a) D = f(l,ρ,μV,g)
b) D = (l,ρ,μV,g)
c) D = f
d) D = f(lpv)
Answer: a
Explanation: The correct format for Rayleigh’s method is D = f(l,ρ,μV,g). Where, D is the dimensional analysis, ‘f’ is the function, and the variables inside the bracket are the physical parameters to determine the function.

5. What does ‘C’ denote in D = ClaρbμcVdge?
a) Function
b) Dimensions
c) Dimensionless constant
d) Number of parameters
Answer: c
Explanation: ‘C’ in D = ClaρbμcVdge denotes dimensionless constant and a,b,c,d,e, are its exponents. This is the fundamental purpose of Rayleigh’s method.

6. Why does Rayleigh’s method have limitations?
a) To many variables
b) Format
c) Exponents in between variables
d) Many exponents
Answer: c
Explanation: The main limitation of the Rayleigh’s method is that it has exponential relationship between the variables. It makes it more complex for solving. Since, more variables with exponents will lead to a confusion in the solving process.

7. Which among the following is same as the Rayleigh’s method?
a) Buckingham method
b) Dead weight method
c) Conveyor method
d) Ionization method
Answer: a
Explanation: Buckingham method is also called as the ‘pi’ theorem method. This method can be illustrated by various moving components. It plays an important role in finding the drag of various moving objects.

8. Which among the following is not a dimensionless number?
a) Reynolds
b) Froude
c) Mach
d) Cartesian
Answer: d
Explanation: Dimensionless numbers are numbers with a dimension of one. It is a pure number. It does not contain any physical unit. No change takes place due to altering of any variable.

9. What is a model analysis?
a) A small-scale replica
b) Actual structure
c) Theory structure.
d) Adopted structure
Answer: a
Explanation: Model analysis is defined as a small-scale replica of the actual structure. Model analysis need not be smaller all the time. They can even be larger than the prototype.

10. What is a prototype?
a) A small-scale replica
b) Actual structure
c) Theory structure.
d) Adopted structure
Answer: b
Explanation: Prototype is the actual structure that needs to be constructed. For a better understanding of the model, we prepare a model analysis. They can even be larger than the prototype.

11. Advantage of a model analysis is_________
a) Performance cannot be predicted
b) The relationships between the variable cannot be obtained
c) Shear stress to thermal diffusivity
d) Alternative designs can be predicted
Answer: d
Explanation: One of the major advantages of the model analysis is that we can predict the alternative designs. It can also predict the performance of the machine in advance.

12. Why do we need a model analysis?
a) For determining the dimensions
b) To provide a safe design
c) To check the shear stress
d) To check the thermal diffusivity
Answer: b
Explanation: One of the major advantages of the model analysis is that we can predict the alternative designs. It provides the safest design in the most economical way.

13. The similarity between the motion of model and prototype is_________
a) Dynamic similarity
b) Potential similarity
c) Kinematic similarity
d) Design similarity
Answer: c
Explanation: Kinematic similarity is defined as the similarity between motion of the model and the prototype. It exists in between the model and prototype. The points in the model and prototype are of the same magnitude.

14. The similarity between the forces of model and prototype is ________
a) Dynamic similarity
b) Potential similarity
c) Kinematic similarity
d) Design similarity
Answer: a
Explanation: Dynamic similarity is defined as the similarity between forces of a model and the prototype. It exists in between the model and prototype. The points in the model and prototype are of the same magnitude.

15. Which among these forces does not act in a moving fluid?
a) Inertial force
b) Viscous force
c) Gravity force
d) Drag
Answer: d
Explanation: Drag does not take place in moving fluids. Moving fluids are restricted by a viscous force and move along an inertial force. The gravitational force tends to act perpendicular to the fluid surface.

16. What is the formula for elastic force?
a) Elastic stress/area
b) Elastic strain/area
c) Elastic stress*area
d) Elastics stress* Elastic strain
Answer: c
Explanation: Elastic force is a force that is developed by a material to retain to its original position. It regains its shape after a period of time. When an elastic material is compressed or stretched, it develops an elastic force.

17. For a dynamic similarity between a model and a prototype, the ratio of their forces in the model and the prototype must be equal.
a) True
b) False
Answer: a
Explanation: For a dynamic similarity between a model and a prototype, the ratio of their forces in the model and the prototype must be equal. It means that the dynamic similarity between a model and a prototype must be the same.

18. Similitude is a concept applicable to the testing of _________
a) Mathematical models
b) Physical models
c) Engineering models
d) Chemical models
Answer: c
Explanation: Similitude is an essential concept that is applicable to the testing of basic engineering models. A model has a similitude with a real-time application. It shares the same geometry. Similarity and similitude are interchangeable at times.

19. Which among the following is the main application for Similitude?
a) Ships
b) Cars
c) Hydraulics
d) Train
Answer: c
Explanation: Similitude plays an important role in various applications. One of the major applications are hydraulics and aerospace engineering. Its main purpose is to test the fluid flow at different conditions of scaled model.

20. Which among the following is not a criteria to achieve similitude?
a) Geometric similarity
b) Kinematic similarity
c) Dynamic similarity
d) Conditional similarity
Answer: d
Explanation: The criteria required to achieve similitude are geometric similarity, kinematic similarity and dynamic similarity. All these similarities play a major role in regard with the real-time applications. Similarity and similitude are interchangeable at times.

21. A model of with same shape is__________
a) Geometric similarity
b) Kinematic similarity
c) Dynamic similarity
d) Conditional similarity
Answer: a
Explanation: Geometric similarity is a similarity that follows a real-time application. It is model that has the same shape for any sort of application. It is measured in scaled quantities.

22. Which among the following have similar fluid streamlines?
a) Geometric similarity
b) Kinematic similarity
c) Dynamic similarity
d) Conditional similarity
Answer: b
Explanation: In kinematic similarity, fluid flow of model and real-time application takes place. Here, the model and the real application must undergo similar time rates in motion changes. Thus, it has similar fluid streamlines.

23. Which among the following have the same forces acting on them?
a) Geometric similarity
b) Kinematic similarity
c) Dynamic similarity
d) Conditional similarity
Answer: c
Explanation: Dynamic similarities have the same forces acting on them. That means, the ratios of all the forces acting on the fluid particles are constant. Also, the ratio of the forces acting on the boundary surfaces are also a constant.

24. All the parameters in a similitude are described using_________
a) Continuum mechanics
b) Solid mechanics
c) Diesel mechanics
d) Aircraft mechanics
Answer: a
Explanation: A branch of mechanics that deals with the analysis of mechanical behaviour of materials and kinematics of materials. They are used for modelling purposes. It is modelled in continuous mass.

25. Physical similitude has exactly the same geometric shape of the prototype.
a) True
b) False
Answer: a
Explanation: Physical similitude is also called the similitude of shape. It is for modelling the same geometric shape as that of its prototype. Which means, that the shape will have to be divided by a scale factor.

26. Which among the following is a standard scale for a similitude?
a) 1:250
b) 1:50
c) 1:25
d) 1:100
Answer: c
Explanation: To design a similitude with a specific dimension, we must fix a scale. The standard system has fixed the scale as 1:25. This was fixed for an uniformity in dimensions.

27. The rate at which the particles of fluid can spread is called_______
a) Surface tension
b) Diffusivity
c) Viscosity
d) Kinetics
Answer: b
Explanation: Diffusivity is defined as the rate of diffusion. It is a measure of particles at which the fluids or heat can spread. They are measured in different mediums. It can be defined on the basis of its properties.

28. Which among the following is the standard symbol for Archimedes number?
a) A
b) AR
c) Ar
d) a
Answer: c
Explanation: The standard symbol for Archimedes number is Ar. Archimedes number in fluid mechanics deals with the motion of fluids. This takes place due to the differences in their densities. It was followed by the Archimedes principle.

29. 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
Answer: a
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.

30. Which among the following is the standard symbol for Atwood number?
a) A
b) AR
c) Ar
d) a
Answer: a
Explanation: The standard symbol for Atwood number is A. Atwood’s number in fluid mechanics deals with the onset of instabilities in mixtures of fluid. It is due to the density differences in fluid.

31. Which among the following is the standard symbol for Blake number?
a) Bi
b) ba
c) Bl
d) b
Answer: b
Explanation: The standard symbol for Blake number is B or Bl. Blake number in fluid mechanics deals with geology, fluid mechanics and porous media. It is due to the inertial over the viscous forces in fluid flow through porous media.

32. Which among the following is the standard symbol for Darcy friction factor?
a) F
b) Fd
c) C
d) Cd
Answer: b
Explanation: The standard symbol for Darcy friction factor is Fd. Darcy friction factor in fluid mechanics deals with fractions of pressure losses. This is due to the development of friction in the pipe.

33. Fanning friction factor is _________
a) 0.25 times Darcy friction factor
b) Same as Darcy friction factor
c) 2 times Darcy friction factor
d) Independent
Answer: a
Explanation: Fanning friction factor is 0.25 times Darcy friction factor. Fanning friction factor in fluid mechanics deals fraction of pressure losses due to friction in the pipe.

34. Which among the following is the standard symbol for Froude number?
a) F
b) Fo
c) Fr
d) f
Answer: c
Explanation: The standard symbol for Froude number is Fr. Froude number in fluid mechanics deals with wave and surface behaviour of fluid particles. This is with the ratio of body’s inertia to gravitational forces.

35. Which among the following is the standard symbol for the Peclet number?
a) P
b) p
c) Pe
d) pe
Answer: c
Explanation: The standard symbol for Peclet’s number is Pe. Peclet’s number in fluid mechanics deals with heat transfer. It is defined as the ratio of transport rate over molecular diffusive transport.