300+ REAL TIME Fluid Mechanics Objective Questions & Answers 2023

250+ TOP MCQs on Newton’s Second Law and Answers

Fluid Mechanics Multiple Choice Questions on “Newton’s Second Law”.

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
Clarification: 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
Clarification: 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
Clarification: 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
Clarification: 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
Clarification: 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
Clarification: 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
Clarification: 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) 100^oC
b) 0^oC
c) 5^oC
d) 0 K
Answer: c
Clarification: 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
Clarification: 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.

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
Clarification: 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.

250+ TOP MCQs on Movement of Piston in Dash Pot and Answers

Fluid Mechanics Multiple Choice Questions on “Movement of Piston in Dash Pot”.

1. The dashpot timer is_______
a) Manual
b) Automatic
c) Controlled
d) Free Movement
Answer: b
Clarification: The dashpot timer is an automatic timer. It is used in several machines and has ‘n’ number of variations. It is used in many applications such as printing presses, generating motors and in many irrigation systems.

2. Mechanical timers measure time using______
a) Thermal Mechanism
b) Computer code
c) Clock
d) Glass
Answer: c
Clarification: Mechanical timers use clock to measure time intervals. It can be categorised into two types. One of them is a stop watch, which measures the elapsed time and the other is an hourglass. Both these methods follow the same principle of recording the time intervals.

3. Which among the following is an oldest mechanical timer?
a) Stop watch
b) Egg-timers
c) Balance wheel
d) Hour glass
Answer: d
Clarification: Hour glass is a device that is used to measure the passage of time. An hour glass contains two glass bulbs connected by a narrow neck. This allows a trickle of material from the upper bulb to the lower one. (Material most commonly used: sand).

4. Electronic timers are essentially ________
a) Quartz clock
b) Stop watch
c) Hour glass
d) Egg-timers
Answer: a
Clarification: Electronic timers are quartz clocks. They are modified with special electronics. They can achieve higher precision when compared to mechanical timers. Electronic timers work on digital electronics which have analog or digital display.

5. Software timers work on__________
a) Quartz glass
b) Balance wheel
c) Computer code
d) Liquid
Answer: c
Clarification: Software timers are not devices or parts of devices. They work on computer code which relies on the accuracy of a clock generator. It is usually built into a hardware device that runs on the principle of software.

6. What type of device is a dashpot?
a) Electronic
b) Mechanical
c) Thermal
d) Computerised
Answer: b
Clarification: A dashpot contains a damper which resists the motion with the help of a viscous flow. The force so produced is directly proportional to the velocity. But, it acts in the opposite direction, thus slowing the motion and absorbing the energy. By this way, the dashpot works on a mechanical basis.

7. What are the types of dashpot?
a) Linear and rotary
b) Reciprocating and nonuniform.
c) Linear and reciprocating
d) Circular and rotational
Answer: a
Clarification: Dashpot is divided into two types, linear and rotary types. Linear dashpots are specified by the amount of linear displacement (stroke) and force per velocity (damping coefficient). Rotary dashpots will have force per velocity( damping coefficient) in torque so developed.

8. Which among the following is not an application of the dashpot?
a) Door closer
b) Consumer electronics
c) Timers
d) Pilot Static Tube
Answer: d
Clarification: 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. Example of amorphous substance is _______
a) Polymers
b) Diamond
c) Snowflakes
d) Quartz
Answer: a
Clarification: Amorphous substances are substances that have an internal structure. These internal structures are made up of interconnected structural blocks. They have a long-range order. A good example of an amorphous substance is a polymer.

10. Which among the following is not a type of crystalline substances?
a) Ionic
b) Metallic
c) Covalent
d) Hydrogen bond
Answer: d
Clarification: A crystalline substance does not undergo hydrogen bonding. A crystalline substance is a substance in which the constituents are arranged in a highly ordered microscopic structure. It forms a crystal lattice in all directions.

11. Fluid sealing in a dashpot is achieved using________
a) Circlips
b) Piston rings
c) Flakes
d) Quartz
Answer: b
Clarification: Fluid sealing in a dashpot is achieved using a piston ring. Piston rings are a number of narrow iron rings which are fitted loosely into the grooves of the piston. The rings split at a point on the rim which is placed just below the crown.

12. Which among the following is the best suitable material for making a piston?
a) Hiduminium
b) Titanium
c) Aluminium
d) Borium
Answer: c
Clarification: Pistons are made from aluminium alloys. The properties of these alloys can be improved by forging technique. Forging is done to improve the fatigue life and strength of the piston.

250+ TOP MCQs on Types of Forces Acting in Moving Fluid and Answers

Fluid Mechanics Multiple Choice Questions on “Types of Forces Acting in Moving Fluid”.

1. Which among the following force is developed due to resistance of a fluid flow?
a) Viscous force
b) Inertial force
c) Gravity force
d) Pressure force
Answer: a
Clarification: Viscous force is the force that is developed due to resistance of a fluid flow. Viscous force is equal to the product of shear stress due to viscosity and surface area of the fluid. It acts in the opposite direction to that of the acceleration.

2. Which among the following force is developed due to resistance in its state of motion?
a) Viscous force
b) Inertial force
c) Gravity force
d) Pressure force
Answer: b
Clarification: Inertial force is the force that has resistance to any physical object that undergoes a change in its state of motion. Inertial force is the product acceleration of fluid and its mass. It acts opposite to the direction of acceleration.

3. Which among the following is the correct formula for gravitational force?
a) F= Gm₁m₂/r²
b) F= Gm₁m₂
c) F= m₁m₂/r²
d) F= Gm₁m₂/r³
Answer: a
Clarification: Gravitational force was derived by Newton’s theory of gravitation. It is defined as the product of mass and acceleration due to gravity of the fluid flow. It is mainly present in cases of open surface fluid flow.

4. Which among the following is present in pipe flow?
a) Viscous force
b) Inertial force
c) Gravity force
d) Pressure force
Answer: d
Clarification: Pressure is a force that is applied perpendicular to the surface of an object over a unit area of force. It is defined as the product of pressure intensity and cross-sectional area of the flowing fluid. Pressure force is present in case of pipe flow.

5. A force that is caused due to attraction of particles in the layer of fluid bulk is called?
a) Viscous force
b) Inertial force
c) Surface tension force
d) Pressure force
Answer: c
Clarification: Surface tension is caused due to the attraction of particles in the surface layer of the fluid in bulk quantities. Surface tension force is defined as the product of surface tension and length of flowing fluid.

6. A force that is needed to bring back the body to its original position is called as?
a) Viscous force
b) Elastic force
c) Gravity force
d) Pressure force
Answer: c
Clarification: Elastic force is the force that brings a body back to its original position. It is defined as the product of elastic stress and the area of the flowing fluid.

7. How do we measure the flow rate of liquid?
a) Coriolis method
b) Dead weight method
c) Conveyor method
d) Ionization method
Answer: a
Clarification: 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. The three major fluid forces are Buoyancy, drag and lift.
a) True
b) False
Answer: a
Clarification: Buoyancy, drag and lift are the three major fluid forces. These forces have significant importance in various applications. For example: Shotput, badminton, cricket, baseball, cycling, swimming etc.

9. The drag force acts in _____ to the flow velocity.
a) Perpendicular direction
b) Same direction
c) Opposite direction
d) Different directions
Answer: c
Clarification: The drag force acts in the opposite direction to that of the relative flow velocity. It acts in the opposite direction with respect to a surrounding fluid flow. Thus, option Opposite direction is correct.

10. Drag force is affected by__________
a) Cross sectional area and smoothness
b) Rigidity and density
c) Pressure and temperature
d) Mass
Answer: a
Clarification: Drag force is affected by cross sectional area and smoothness. If it is affected by cross sectional area, then it is called form drag. If it is affected by surface smoothness, then it is called as surface drag.

11. The lift force acts in _____ to the flow velocity.
a) Perpendicular direction
b) Same direction
c) Opposite direction
d) Different directions
Answer: a
Clarification: The lift force acts in the perpendicular direction to that of the relative flow velocity. It acts in the perpendicular direction with respect to a surrounding fluid flow. Thus, option Perpendicular direction is correct.

12. Which among the following is the correct formula for drag?
a) D = Cd * A * 0.5 * r * V²
b) D = Cd * A * 0.5 * r * V*2
c) D = Cd * A * 0.5 * r * V/2
d) D = 0.5 * r * V
Answer: a
Clarification: The drag force acts in the opposite direction to that of the relative flow velocity. It acts in the opposite direction with respect to a surrounding fluid flow. Thus, the correct option is D = Cd * A * 0.5 * r * V².

13. Which among the following is the correct formula for lift?
a) D = Cl * A * 0.5 * r * V²
b) D = Cl * A * 0.5 * r * V*2
c) D = Cl * A * 0.5 * r * V/2
d) D = 0.5 * r * V
Answer: a
Clarification: The lift force is a force that acts in the perpendicular direction to that of the relative flow velocity. It acts in the perpendicular direction with respect to a surrounding fluid flow. Thus, the correct option is D = Cl * A * 0.5 * r * V².

250+ TOP MCQs on Geometrical Properties of Triangular Section – 2 and Answers

Advanced Fluid Mechanics Questions and Answers on “Geometrical Properties of Triangular Section – 2”.

1. Determine the Hydraulic depth for a triangular channel having side slope of 1H:3V and depth 15m.
a) 30m
b) 15m
c) 7.5m
d) 3.75m
Answer: c
Clarification: Hydraulic Depth = y/2
= 15/2
= 7.5m.

2. Calculate the Hydraulic Radius for a triangular channel having side slope 2H:4V and a depth of 3m.
a) 0.68m
b) 0.67m
c) 0.66m
d) 0.65m
Answer: b
Clarification:

3. The Hydraulic Depth of a triangular channel is 5m, calculate the normal depth of the channel.
a) 8m
b) 10m
c) 12m
d) 14m
Answer: b
Clarification: D = y/2
y = 2D = 10m.

4. The hydraulic radius of a triangular section is 0.45m and the normal depth of the channel is 2m, calculate the side slope of the channel.
a) 1/4
b) 1/3
c) 1/2
d) 1
Answer: c
Clarification:

5. The ratio between hydraulic radius and hydraulic depth of a triangular channel is 31/100, calculate the side slope of the channel.
a) 1⁄2
b) 1⁄3
c) 1⁄4
d) 2⁄3
Answer: b
Clarification: