# Multiple-Choice Questions or Objective Type Questions on Fluid Mechanics [PDF Included]

Are you getting bored in studying the textbooks? For removing the boringness, I am keeping here a lot of Multiple-Choice Questions on Fluid Mechanics, Fluids, Properties of Fluid, and the Non-dimensional numbers in a Fluid Flow. I am sure that it will help you a lot.

In the last section, there will be a Quiz test of 10 marks on Fluid Mechanics. Appear for the test and fall in love with studying a lot of objective-type questions.

Now, let’s start the objective type questions or viva questions.

## MCQ Questions or Viva Questions on Fluids

• Fluid is a substance that ____.
1. Intermittently deforms
2. Resists deformation
3. Continuously deforms
4. Can’t resist shear force applied on them
5. Both 3 and 4

Ans: (5)

• Which of the following substances don’t have free surfaces?
1. Solid
2. Liquid
3. Gases
4. Both 1 &2

Ans: (3)

• What do you think about a Compressible fluid?
1. It has fixed density
2. It has variable density
3. Can’t say

Ans: (2)

• What do you think about an Incompressible fluid?
1. It has fixed density
2. It has variable density
3. Can’t say

Ans: (1)

• By which of the following you can measure the compressibility characteristics of a fluid?
1. Reynolds number
2. Grashoff number
3. Mach number
4. None of these

Ans: (3)

• Which one of the following will you treat as ideal liquid?
1. Air
2. Water
3. Oil
4. None of these

Ans: (2)

• Which one of the following will you treat as an ideal gas?
1. Air
2. Water
3. Oil
4. None of these

Ans: (1)

• What do you think about an ideal fluid ____?
1. Compressible
2. Incompressible
3. Can’t say

Ans: (2)

• A real fluid is considered as ____.
1. Compressible
2. Incompressible
3. Cant’t say

Ans: (1)

• Which of the following should be treated as incompressible?
1. Ideal fluid
2. Real fluid
3. Solid
4. Can’t say

Ans: (1)

## MCQ Questions or Viva Questions on Fluid Properties

• The unit of specific weight is:
1. Kg/m^3
2. N/m^3
3. M^3/kg
4. None of these

Ans: (2)

• Kinematic viscosity is the ratio of ____.
1. Density and dynamic viscosity of the fluid
2. Velocity gradient and density of the fluid
3. Dynamic viscosity and density of the fluid
4. Density and velocity gradient of the fluid

Ans: (3)

• Stoke is the unit of:
1. Specific gravity
2. Dynamic viscosity
3. Kinematic viscosity
4. None of these

Ans: (3)

• One stoke is equal to ____.
1. 10-2 m2/sec
2. 10-3 m2/sec
3. 10-1 m2/sec
4. 10-4 m2/sec

Ans: (4)

• Newton’s law of viscosity is ____.
1. Shear stress is inversely proportional to rate of shear strain
2. Shear strain is inversely proportional to shear stress
3. Shear stress is directly proportional to rate of shear strain
4. Shear stress = rate of shear strain

Ans: (3)

• Which one of the following is a wrong statesman?
1. The viscosity of an ideal fluid is zero
2. The viscosity of real fluid is zero
3.  Water and air are Newtonian fluid
4.  Milk is a non-Newtonian fluid

Ans: (2)

• Poise is the unit of ____.
1. Kinematic viscosity
2. Dynamic viscosity
3. Specific weight
4. Specific gravity

Ans: (2)

• Which one of the following is not a Newtonian fluid?
1. Water
2. Air
3. Tooth-paste
4. None of these

Ans: (3)

• Mach number is the ratio of ____.
1. (Velocity of a fluid)/(velocity of sound)
2. (Velocity of sound)/(velocity of a fluid)
3. Velocity of sound – velocity of a fluid
4. (Velocity of a fluid)2/(velocity of sound)

Ans: (1)

• Fly ash is the example of ____.
1. Dilatant fluid
2. Bingham fluid
3. Newtonian fluid
4. None of these

Ans: (2)

• For an incompressible flow, the Mach number is ____.
1. Greater than 0.3
2. Equal to 0.3
3. Less than 0.3
4. 1

Ans: (3)

• For a compressible subsonic flow, Mach number is____.
1. Greater than 0.3 and less than 1
2. Equal to 0.3
3. Less than 0.3
4. 1

Ans: (1)

• Bulk modulus is the ratio of ____.
1. Volumetric stress and increase of pressure
2. Volumetric strain and increase of pressure
3. Increase of pressure and volumetric stress
4. Increase of pressure and volumetric strain

Ans: (4)

• Compressibility is the ratio of ____.
1. Volumetric stress and increase of pressure
2. Volumetric strain and increase of pressure
3. Increase of pressure and volumetric stress
4. Increase of pressure and volumetric strain

Ans: (2)

• The unit of surface tension is:
1. m2/sec
2. N/m2
3. N/m
4. None of these

Ans: (3)

• Surface tension on a liquid droplet is ____ (where d is the diameter of the droplet and σ is the surface tension.)
1. 2σ/d
2. 4σ/d
3. 8σ/d
4. σ/d

Ans: (2)

• Surface tension on a hollow bubble is ____ (where d is the diameter of the droplet and σ is the surface tension.)
1. 2σ/d
2. 4σ/d
3. 8σ/d
4. σ/d

Ans: (3)

• Surface tension on a liquid jet is ____ (where d is the diameter of the droplet and σ is the surface tension.)
1. 2σ/d
2. 4σ/d
3. 8σ/d
4. σ/d

Ans: (1)

## MCQ Questions or Viva Questions on Fluid Mechanics

Fluid mechanics has two branches. One is fluid statics and another one is fluid dynamics. When there is no movement of the fluid or you can say that the fluid is at rest; the mechanics involved here is fluid statics. When there is the involvement of fluid movement, it is termed fluid dynamics.

### MCQ Questions or Viva Questions on Fluid Statics

• When ____, you will see that Vaporisation occurs.
1. Vapor pressure at a temperature is less than the pressure above the liquid surface at the same temperature.
2.  Vapor pressure at a temperature is equal to the pressure above the liquid surface at the same temperature.
3. Vapor pressure at a temperature is greater than the pressure above the liquid surface at the same temperature.
4. None of the above

Ans: (3)

• When ____, you will see that boiling occurs.
1. Vapor pressure at a temperature is less than the pressure above the liquid surface at the same temperature.
2.  Vapor pressure at a temperature is equal to the pressure above the liquid surface at the same temperature.
3. Vapor pressure at a temperature is greater than the pressure above the liquid surface at the same temperature.
4. None of the above

Ans: (2)

• Which of the following law states that the intensity of pressure at any point within a static fluid is the same in all directions?
1. Pascal’s law
2. Charles law
3. Boyle’s law
4. Archimedes law

Ans: (1)

• Which of the following statesman is not correct?
1. Absolute pressure- atmospheric pressure= gauge pressure
2. Atmospheric pressure- absolute pressure= vacuum pressure
3. Atmospheric pressure + gauge pressure = absolute pressure
4. Atmospheric pressure + absolute pressure = gauge pressure

Ans: (4)

• Metacentre is the intersection of ____.
1. Buoyant force and the centreline of the body.
2. Centreline of the body and the centre of gravity
3. Buoyant force and the centre of gravity
4. None of these

Ans: (1)

• When a body is kept inside water, it will be in stable equilibrium if ____( where, M is the metacentre and G is the centre of gravity).
1. M is below G
2. M is above G
3. M is at G i.e. both points coincide
4. None of these

Ans: (2)

• When a body is kept inside water, it will be in unstable equilibrium if ____( where, M is the metacentre and G is the centre of gravity).
1. M is below G
2. M is above G
3. M is at G i.e. both points coincide
4. None of these

Ans: (1)

• When a body is kept inside water, it will be in neutral equilibrium if ____( where, M is the metacenter and G is the center of gravity).
1. M is below G
2. M is above G
3. M is at G i.e. both points coincide
4. None of these

Ans: (3)

• Comparison of viscosity is done by ____.
1. Red wood viscometer
2. Piezometer
3. Manometer
4. None of these

Ans: (1)

• Which of the following is defined as centre of buoyancy?
1. Centre of gravity of the body
2. Centroid of the fluid displaced by the body
3. Middle point between C.G and Metacentre
4. None of these

Ans: (2)

• When the temperature of a gas rises, the viscosity ____.
1. Increases
2. Decreses
3. Remain constant
4. Can’t say

Ans: (1)

• Viscosity of water is ____.
1. Less than that of oil
2. More than that of honey
3. More than that of oil
4. None of these

Ans: (1)

• A balloon is moving in the air. It follows the law of ____.
1. Buoyancy
2. Archimedes
3. Gravitation
4. None of these

Ans: (2)

• The pressure of oil is equivalent to 40 metre of water column. Specific gravity of oil is 0.80. What is the pressure of oil in terms of metre?
1. 32 metre
2. 500 metre
3. 50 metre
4. 320 metre

Ans: (3)

• The specific gravity of fluid is 0.85. The viscosity of this fluid is 0.0085 N-Sec/m2. Its kinematic viscosity in m2/sec is ____.
1. 0.0001
2. 0.00001
3. 0.001
4. 0.01

Ans: (2)

• Which of the following phenomenon is responsible for the shape of the raindrop as spherical?
1. Buoyancy
2. Viscosity
3. Surface tension
4. Atmospheric pressure

Ans: (3)

• By which of the following instrument, you can measure specific gravity?
1. Pirani gauge
2. Manometer
3. Hydrometer
4. Piezometer

Ans: (3)

• Cavitation occurred in a fluid is due to ____.
1. High pressure
2. High viscosity
3. Low pressure
4. Low viscosity

Ans: (3)

• If the surface of a liquid is concave, the cohesion force is ____.
1. Decreased
2. Increased
3. Zero
4. Can’t say.

Ans: (1)

### MCQ Questions or Viva Questions on Fluid Dynamics

• How will you come to know that the flow is laminar?
1. By Reynolds number
2. By viscosity of the fluid
3. By Grashoff number
4. None of these

Ans: (1)

• In case of laminar flow, the flow-losses are ____.
1. Proportional to V2
2. Proportional to V
3. Inversely proportional to V
4. Inversely proportional to V2

Ans: (2)

• In case of turbulent flow, the flow-losses are ____.
1. Proportional to V2
2. Proportional to V
3. Inversely proportional to V
4. Inversely proportional to V2

Ans: (1)

• When Reynolds number is less than 2000, the flow is ____.
1. Turbulent
2. Laminar
3. Transient
4. Can’t say

Ans: (2)

• When Reynolds number is more than 10,000, the flow is ____.
1. Turbulent
2. Laminar
3. Transient
4. Can’t say

Ans: (1)

• When the fluid properties don’t change with respect to time, the flow is ____.
1. Uniform flow
2. Non-uniform flow

Ans: (3)

• When the fluid properties don’t change with respect to the position at a particular time, the flow is ____.
1. Uniform flow
2. Non-uniform flow

Ans: (1)

• The continuity equation for a two dimensional flow is:
1. ∂u/∂x – ∂v/∂y =0
2. ∂u/∂x + ∂v/∂y =0
3. ∂u/∂y + ∂v/∂x =0
4. ∂u/∂y – ∂v/∂x =0

Ans: (2)

• For irrotational flow, the flow equation is:
1. 2u/∂x2 – ∂2v/∂y2 =0
2. ∂Ψ /∂y + ∂Ψ /∂y=0
3. 2Ψ/∂x2 – ∂2 Ψ /∂y2= 0
4. 2 Ψ /∂x2 + ∂2 Ψ /∂y2= 0

Ans: (4)

• In a pipe flow, which of the following relation is true for a laminar flow?
1. Velocity, V= Umax
2. Velocity V = 0.5 Umax
3. Velocity V = 0.25 Umax
4. Velocity V = 0.75 Umax

Ans: (2)

• For which of the following cases, you should use Navier Stokes Equation?
1. Viscous flow
2. Non- viscous flow
3. Turbulent flow
4. Rotational flow

Ans: (1)

• In which case, you can apply Bernoulli’s Equation?
3. Rotational flow
4. None of these

Ans: (2)

• Darcy’s Friction Factor is ____ (Where Re is the Reynolds Number) When there is a laminar flow in a smooth pipe.
1. 32/Re
2. 16/ Re
3. 8/ Re
4. 0.0791/ Re

Ans: (2)

## MCQ on Non-Dimensional Numbers in a Fluid Flow

• Which of the following ratio is the Reynolds number?
1. Inertia force and viscous force
2. Viscous force and inertia force
3. Thermal conductivity and viscous force
4. Thermal conductivity and inertia force

Ans: (1)

• Which of the following ratio will give you Froude number?
1. Inertial force / viscous force
2. Viscous force / inertial force
3. Gravitational force /viscous force
4. Inertial force / gravitational force

Ans: (4)

• In a tranquil flow in an open channel,
1. Depth of water = critical depth
2. Depth of water > critical depth
3. Depth of water < critical depth
4. Can’t say

Ans: (2)

• Which of the following ration indicates Prandtle number?
1. Inertial force and viscous force
2. Viscous force and inertial force
3. Momentum diffusivity and thermal diffusivity
4. Thermal diffusivity and momentum diffusivity

Ans: (3)

• Which of the following ratio determines the Nusselt number?
1. Inertial force and viscous force
2. Viscous force and inertial force
3. Convection heat transfer and conduction heat transfer
4. Conduction heat transfer and convection heat transfer

Ans: (3)

• Which of the following parameter determines Biot number?
1. Convective heat transfer and conductive heat transfer of the body
2. Conductive heat transfer of the fluid and convective heat transfer
3. (External resistance to heat convection / Internal resistance to heat conduction of a body)
4. (Internal resistance to heat conduction of the body / external resistance to heat convection)
5. Both 1 and 4

Ans: (5)

• Which of the following is the Weber number?
1. Inertia force / gravitational force
2. Inertia force / surface tension
3. Gravitational force / surface tension
4. Gravitational force / inertia force

Ans: (2)

• Which of the following ratio indicates the Euler number?
1.  Inertia force / pressure fore
2. Inertia force / gravitational force
3. Pressure force / inertia force
4. Gravitational force / surface tension

Ans: (3)

• Which ratio determines the Fourier number?
1. Inertia force / surface tension
2. Inertia force / viscous force
3. Thermal diffusivity / momentum diffusivity
4. Diffusive transport rate of heat / storage rate of heat

Ans: (4)

• ____ ratio determines the Lewis number.
1. Mass diffusivity / thermal diffusivity
2. Thermal diffusivity / mass diffusivity
3. Thermal diffusivity / momentum diffusivity
4. Momentum diffusivity / mass diffusivity

Ans: (2)

• Which of the following ratio determines the value of Peclet Number?
1. Advective transport rate / thermal diffusive transport rate
2. Thermal diffusive transport rate / advective transport rate
3. Mass diffusive transport rate / advective transport rate
4. None of these

Ans: (1)

• Which of the following ratio determines the value of Rayleigh Number?
1. Inertia force / viscous force
2. Buoyancy force / viscous force
3. Viscous force / buoyance force
4. Viscous force / inertia force

Ans: (2)

• Which of the following ratio determines the value of Taylor Number?
1. Inertia force due to rotation / viscous force of a fluid
2. Viscous force / inertia force of a fluid due to rotation of a fluid
3. Buoyancy force / viscous force of a fluid
4. Viscous force / buoyance force of a fluid

Ans : (1)

## Quiz on Fluid Mechanics

Here is the Quiz for you:

27
Created on

Quiz on Fluid Mechanics

1 / 10

When there is sudden enlargement in the cross-section of the pipe, it faces the loss of head. It is due to ____.

2 / 10

How does the head of a pipe changes with the flow in the pipe when the diameter of the pipe is constant?

3 / 10

How does the head loss get affected by velocity in a pipe when there is turbulent flow?

4 / 10

Which of the following is not a Non-dimensional number?

5 / 10

For Supersonic flow, the value of the Mach number is ____.

6 / 10

Which of the following is Dilatant fluid?

7 / 10

Blood is a ____ type of fluid.

8 / 10

How does Viscosity get affected when the temperature of gas increases?

9 / 10

How does Viscosity get affected when the temperature of liquid increases?

10 / 10

How does Surface tension get affected when temperature increases?

The average score is 48%

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## Conclusion

I hope that the Multiple-Choice Questions on Fuels will help you in your college/university examinations and in different types of competitive examinations. I will be more encouraged if I get feedback from your end. Please don’t forget to give the feedback by writing in the comment box. Good Luck!