100 Important Basic MCQs (Level -1) on Fluid Dynamics, Physics (Unit-Wise MCQs Practice):
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Fluid Dynamics MCQs (Level 1) – 100 Basic MCQs (MCQs 1–100)
MCQs No. 1
Which of the following best defines a fluid?
a. A substance that always retains a fixed shape
b. A substance that cannot flow
c. A substance that continuously deforms under an applied shear force
d. A rigid body with constant volume
The Correct Answer is option c. A substance that continuously deforms under an applied shear force
Explanation:
A fluid is any substance (liquid or gas) that continuously changes its shape and flows when subjected to even a small shear force.
MCQs No. 2
An incompressible fluid is one whose:
a. Pressure remains constant
b. Density remains constant
c. Velocity remains constant
d. Temperature remains constant
The Correct Answer is option b. Density remains constant
Explanation:
An incompressible fluid has nearly constant density during its motion. Most liquids are treated as incompressible under ordinary conditions.
MCQs No. 3
An ideal fluid is assumed to be:
a. Compressible and viscous
b. Incompressible and non-viscous
c. Compressible and turbulent
d. Viscous and compressible
The Correct Answer is option b. Incompressible and non-viscous
Explanation:
An ideal fluid is a hypothetical fluid that has no viscosity and cannot be compressed. This assumption simplifies many fluid dynamics calculations.
MCQs No. 4
Steady flow is the flow in which:
a. Velocity changes randomly with time
b. Fluid particles move in circular paths
c. Fluid properties at a point remain constant with time
d. Pressure becomes zero everywhere
The Correct Answer is option c. Fluid properties at a point remain constant with time
Explanation:
In steady flow, properties such as velocity, pressure, and density remain constant with time at every fixed point in the fluid.
MCQs No. 5
Flow in which fluid particles move along smooth and well-defined paths is called:
a. Turbulent flow
b. Chaotic flow
c. Laminar (streamline) flow
d. Rotational flow
The Correct Answer is option c. Laminar (streamline) flow
Explanation:
In laminar or streamline flow, adjacent layers of fluid move smoothly without mixing.
MCQs No. 6
Which type of flow is characterized by irregular and random motion of fluid particles?
a. Laminar flow
b. Uniform flow
c. Turbulent flow
d. Ideal flow
The Correct Answer is option c. Turbulent flow
Explanation:
Turbulent flow contains irregular motion, vortices, and continuous mixing of fluid layers.
MCQs No. 7
The maximum velocity at which a fluid continues to flow smoothly is known as:
a. Terminal velocity
b. Escape velocity
c. Critical velocity
d. Average velocity
The Correct Answer is option c. Critical velocity
Explanation:
Critical velocity is the highest velocity up to which the flow remains laminar. Beyond this speed, turbulence begins.
MCQs No. 8
Flow changes from laminar to turbulent when the fluid speed exceeds:
a. Escape velocity
b. Critical velocity
c. Average velocity
d. Terminal velocity
The Correct Answer is option b. Critical velocity
Explanation:
When the velocity exceeds the critical value, inertial forces dominate over viscous forces, producing turbulent flow.
MCQs No. 9
The equation of continuity is based on the law of conservation of:
a. Energy
b. Force
c. Mass
d. Momentum
The Correct Answer is option c. Mass
Explanation:
The continuity equation states that mass can neither be created nor destroyed during fluid flow.
MCQs No. 10
For a steady incompressible fluid, the equation of continuity is:
a.
b.
c.
d.
The Correct Answer is option c.
Explanation:
For incompressible flow, the product of cross-sectional area and velocity remains constant throughout the pipe.
MCQs No. 11
The SI unit of volume flow rate is:
a. m² s⁻¹
b. kg s⁻¹
c. m³ s⁻¹
d. m s⁻¹
The Correct Answer is option c. m³ s⁻¹
Explanation:
Volume flow rate is the volume of fluid passing through a cross-section per unit time. Its SI unit is cubic metre per second (m³ s⁻¹).
MCQs No. 12
Volume flow rate of a fluid is given by:
a. Q = Pv
b. Q = Av
c. Q = ρv
d. Q = mg
The Correct Answer is option b. Q = Av
Explanation:
Volume flow rate is the product of the cross-sectional area of the pipe and the velocity of the fluid.
MCQs No. 13
If the cross-sectional area of a pipe decreases, the velocity of an incompressible fluid:
a. Decreases
b. Remains constant
c. Increases
d. Becomes zero
The Correct Answer is option c. Increases
Explanation:
According to the equation of continuity (Av = constant), a decrease in area causes an increase in fluid velocity.
MCQs No. 14
Which quantity remains constant throughout a steady incompressible flow?
a. Pressure
b. Velocity
c. Mass flow rate
d. Temperature
The Correct Answer is option c. Mass flow rate
Explanation:
The same mass of fluid passes through every cross-section of the pipe each second.
MCQs No. 15
Bernoulli's equation is applicable to:
a. Compressible viscous fluids
b. Ideal fluids
c. Turbulent fluids only
d. Rotational fluids only
The Correct Answer is option b. Ideal fluids
Explanation:
Bernoulli's equation assumes the fluid is incompressible, non-viscous, and flowing steadily.
MCQs No. 16
Bernoulli's equation is based on the law of conservation of:
a. Mass
b. Momentum
c. Energy
d. Charge
The Correct Answer is option c. Energy
Explanation:
Bernoulli's equation states that the total mechanical energy of a fluid remains constant along a streamline.
MCQs No. 17
According to Bernoulli's principle, if the speed of a fluid increases, its pressure:
a. Increases
b. Remains constant
c. Decreases
d. Becomes zero
The Correct Answer is option c. Decreases
Explanation:
Higher fluid speed is associated with lower pressure in a moving fluid.
MCQs No. 18
The dynamic pressure of a moving fluid is given by:
a. ρv
b. ρv²
c. ½ρv²
d. ρgh
The Correct Answer is option c. ½ρv²
Explanation:
Dynamic pressure represents the kinetic energy per unit volume of the moving fluid.
MCQs No. 19
Which instrument measures the rate of fluid flow using Bernoulli's principle?
a. Barometer
b. Hydrometer
c. Venturi meter
d. Thermometer
The Correct Answer is option c. Venturi meter
Explanation:
A Venturi meter measures the flow rate of a fluid by comparing pressures at different sections of a pipe.
MCQs No. 20
An atomizer works on the principle of:
a. Pascal's law
b. Archimedes' principle
c. Bernoulli's principle
d. Newton's second law
The Correct Answer is option c. Bernoulli's principle
Explanation:
Fast-moving air creates a low-pressure region that draws liquid upward and sprays it as fine droplets.
MCQs No. 21
The lift acting on an aircraft wing is mainly due to:
a. Weight of air
b. Magnetic force
c. Pressure difference
d. Frictional force
The Correct Answer is option c. Pressure difference
Explanation:
Air moves faster over the curved upper surface of the wing, producing lower pressure than below the wing and creating lift.
MCQs No. 22
Viscosity is the property of a fluid that:
a. Increases its density
b. Opposes the relative motion of adjacent fluid layers
c. Reduces its temperature
d. Increases its pressure
The Correct Answer is option b. Opposes the relative motion of adjacent fluid layers
Explanation:
Viscosity is the internal friction between adjacent layers of a moving fluid.
MCQs No. 23
The SI unit of coefficient of viscosity is:
a. Pascal (Pa)
b. N m⁻²
c. N s m⁻²
d. kg m⁻³
The Correct Answer is option c. N s m⁻²
Explanation:
The SI unit of dynamic viscosity is newton-second per square metre (N s m⁻²), which is also written as pascal-second (Pa·s).
MCQs No. 24
For most liquids, the viscosity with increasing temperature:
a. Increases
b. Remains constant
c. Decreases
d. Becomes zero
The Correct Answer is option c. Decreases
Explanation:
As temperature rises, intermolecular attraction decreases, allowing the liquid to flow more easily.
MCQs No. 25
When the drag force acting on a falling body becomes equal to its weight, the body attains:
a. Escape velocity
b. Critical velocity
c. Terminal velocity
d. Average velocity
The Correct Answer is option c. Terminal velocity
Explanation:
At terminal velocity, the drag force balances the weight of the body. The net force becomes zero, so the body continues to fall with constant speed.
MCQs No. 26
The drag force acting on a body moving slowly through a viscous fluid is directly proportional to:
a. Velocity²
b. Velocity
c. Radius²
d. Density
The Correct Answer is option b. Velocity
Explanation:
According to Stokes' law, for slow-moving bodies in a viscous fluid, the drag force is directly proportional to the velocity.
MCQs No. 27
At terminal velocity, the acceleration of a falling body is:
a. Maximum
b. Minimum
c. Zero
d. Infinite
The Correct Answer is option c. Zero
Explanation:
At terminal velocity, the weight of the body is balanced by the drag force, making the net force and acceleration zero.
MCQs No. 28
Reynolds number is used to determine the:
a. Pressure of a fluid
b. Density of a fluid
c. Nature of fluid flow
d. Volume flow rate
The Correct Answer is option c. Nature of fluid flow
Explanation:
Reynolds number predicts whether the flow of a fluid is laminar or turbulent.
MCQs No. 29
Reynolds number is the ratio of:
a. Pressure force to gravitational force
b. Inertial force to viscous force
c. Weight to buoyant force
d. Velocity to acceleration
The Correct Answer is option b. Inertial force to viscous force
Explanation:
Reynolds number compares inertial forces with viscous forces acting on a flowing fluid.
MCQs No. 30
Laminar flow generally occurs when the Reynolds number is:
a. Very high
b. Low
c. Infinite
d. Zero only
The Correct Answer is option b. Low
Explanation:
A low Reynolds number indicates that viscous forces dominate, producing smooth laminar flow.
MCQs No. 31
Which factor does NOT significantly affect the Reynolds number?
a. Fluid velocity
b. Fluid density
c. Coefficient of viscosity
d. Atmospheric pressure
The Correct Answer is option d. Atmospheric pressure
Explanation:
Reynolds number depends on density, velocity, pipe diameter (or characteristic length), and viscosity—not on atmospheric pressure.
MCQs No. 32
The SI unit of Reynolds number is:
a. m/s
b. Pascal
c. Newton
d. It has no unit
The Correct Answer is option d. It has no unit
Explanation:
Reynolds number is a dimensionless quantity because it is the ratio of two forces.
MCQs No. 33
Which of the following promotes turbulent flow?
a. Low velocity
b. High viscosity
c. High velocity
d. Small Reynolds number
The Correct Answer is option c. High velocity
Explanation:
High fluid velocity increases inertial effects, making turbulent flow more likely.
MCQs No. 34
The coefficient of viscosity mainly depends upon the:
a. Shape of the container
b. Nature of the fluid
c. Colour of the liquid
d. Volume of the container
The Correct Answer is option b. Nature of the fluid
Explanation:
Different fluids have different intermolecular forces, resulting in different viscosities.
MCQs No. 35
The internal friction between adjacent layers of a moving fluid is called:
a. Surface tension
b. Viscosity
c. Elasticity
d. Buoyancy
The Correct Answer is option b. Viscosity
Explanation:
Viscosity is the resistance offered by one layer of a fluid to the motion of another layer.
MCQs No. 36
The SI unit of pressure is:
a. Newton
b. Joule
c. Pascal
d. Watt
The Correct Answer is option c. Pascal
Explanation:
Pressure is measured in pascal (Pa), which is equal to one newton per square metre.
MCQs No. 37
Pressure is defined as:
a. Force per unit volume
b. Work per unit time
c. Force per unit area
d. Energy per unit mass
The Correct Answer is option c. Force per unit area
Explanation:
Pressure is the normal force acting per unit area of a surface.
MCQs No. 38
The pressure of a fast-moving fluid is:
a. Higher than that of a slow-moving fluid
b. Lower than that of a slow-moving fluid
c. Equal to atmospheric pressure
d. Always zero
The Correct Answer is option b. Lower than that of a slow-moving fluid
Explanation:
According to Bernoulli's principle, fluid pressure decreases as its speed increases.
MCQs No. 39
The speed of efflux of a liquid from a small hole is determined by:
a. Pascal's law
b. Newton's law
c. Torricelli's theorem
d. Hooke's law
The Correct Answer is option c. Torricelli's theorem
Explanation:
Torricelli's theorem states that the speed of efflux is equal to the speed acquired by a body falling freely through the same vertical height.
MCQs No. 40
According to Torricelli's theorem, the speed of efflux depends upon the:
a. Area of the hole
b. Density of the liquid
c. Depth of the liquid above the hole
d. Shape of the container
The Correct Answer is option c. Depth of the liquid above the hole
Explanation:
The speed of efflux is given by , where is the depth of the liquid above the opening.
MCQs No. 41
The mathematical expression for the speed of efflux is:
a. v = gh
b. v = √(2gh)
c. v = 2gh
d. v = h/g
The Correct Answer is option b. v = √(2gh)
Explanation:
This equation is known as Torricelli's theorem and is derived from Bernoulli's equation.
MCQs No. 42
A streamlined body experiences:
a. Greater drag force
b. Less drag force
c. No drag force
d. Infinite drag force
The Correct Answer is option b. Less drag force
Explanation:
A streamlined shape reduces turbulence and drag, allowing smoother motion through a fluid.
MCQs No. 43
The shape of an aircraft wing is called:
a. Venturi tube
b. Aerofoil
c. Nozzle
d. Diffuser
The Correct Answer is option b. Aerofoil
Explanation:
An aerofoil is specially designed to produce lift by creating a pressure difference above and below the wing.
MCQs No. 44
The lift produced by an aerofoil is mainly due to:
a. Increased density of air
b. Pressure difference between the upper and lower surfaces
c. Weight of the aircraft
d. Friction between the wing and air
The Correct Answer is option b. Pressure difference between the upper and lower surfaces
Explanation:
Air moves faster over the curved upper surface, lowering pressure and producing lift.
MCQs No. 45
Blood generally flows through healthy arteries in:
a. Turbulent flow
b. Laminar flow
c. Rotational flow
d. Random flow
The Correct Answer is option b. Laminar flow
Explanation:
Under normal conditions, blood flows smoothly in parallel layers through arteries.
MCQs No. 46
Which blood vessels are the smallest in the human body?
a. Arteries
b. Veins
c. Capillaries
d. Aorta
The Correct Answer is option c. Capillaries
Explanation:
Capillaries are the smallest blood vessels where exchange of gases, nutrients, and wastes occurs.
MCQs No. 47
The coefficient of drag is a:
a. Vector quantity
b. Scalar quantity with unit
c. Dimensionless quantity
d. Force
The Correct Answer is option c. Dimensionless quantity
Explanation:
The drag coefficient has no units and depends mainly on the shape of the object and flow conditions.
MCQs No. 48
Which of the following reduces drag force most effectively?
a. Increasing surface roughness
b. Increasing cross-sectional area
c. Giving the body a streamlined shape
d. Increasing fluid density
The Correct Answer is option c. Giving the body a streamlined shape
Explanation:
A streamlined shape allows the fluid to flow smoothly around the body, minimizing drag.
MCQs No. 49
Which physical property mainly resists the flow of a fluid?
a. Density
b. Pressure
c. Viscosity
d. Volume
The Correct Answer is option c. Viscosity
Explanation:
Viscosity provides internal resistance to the motion of fluid layers and opposes fluid flow.
MCQs No. 50
Fluid dynamics is the branch of physics that studies:
a. Solids at rest only
b. Heat transfer in solids
c. Motion of liquids and gases and the forces acting on them
d. Motion of planets only
The Correct Answer is option c. Motion of liquids and gases and the forces acting on them
Explanation:
Fluid dynamics deals with the motion of fluids (liquids and gases) and explains concepts such as continuity, Bernoulli's principle, viscosity, drag force, and terminal velocity.
MCQs No. 51
The equation of continuity for an incompressible fluid is derived from the law of:
a. Conservation of momentum
b. Conservation of mass
c. Conservation of energy
d. Newton's second law
The Correct Answer is option b. Conservation of mass
Explanation:
The equation of continuity states that the mass of fluid entering a pipe per second is equal to the mass leaving it per second.
MCQs No. 52
The mass flow rate of a fluid is given by:
a. ρAv
b. Av
c. Pv
d. ρgV
The Correct Answer is option a. ρAv
Explanation:
Mass flow rate equals density × cross-sectional area × velocity.
MCQs No. 53
If the diameter of a pipe is reduced, the speed of an incompressible fluid:
a. Decreases
b. Remains unchanged
c. Increases
d. Becomes zero
The Correct Answer is option c. Increases
Explanation:
A smaller cross-sectional area requires a higher fluid speed to maintain the same flow rate.
MCQs No. 54
Which of the following is NOT an assumption of Bernoulli's equation?
a. Steady flow
b. Non-viscous fluid
c. Compressible fluid
d. Incompressible fluid
The Correct Answer is option c. Compressible fluid
Explanation:
Bernoulli's equation is valid for steady, incompressible, and non-viscous fluid flow.
MCQs No. 55
The pressure energy per unit volume of a fluid is represented by:
a. P
b. ½ρv²
c. ρgh
d. mv²
The Correct Answer is option a. P
Explanation:
Pressure itself represents the pressure energy per unit volume of a fluid.
MCQs No. 56
The kinetic energy per unit volume of a moving fluid is:
a. ρgh
b. P
c. ½ρv²
d. mgh
The Correct Answer is option c. ½ρv²
Explanation:
The kinetic energy per unit volume of a fluid is called dynamic pressure.
MCQs No. 57
The potential energy per unit volume of a fluid is:
a. P
b. ρgh
c. ½ρv²
d. mgh
The Correct Answer is option b. ρgh
Explanation:
Potential energy per unit volume depends on the height of the fluid above the reference level.
MCQs No. 58
Which of the following quantities remains constant along a streamline according to Bernoulli's equation?
a. Pressure only
b. Velocity only
c. Total mechanical energy per unit volume
d. Density only
The Correct Answer is option c. Total mechanical energy per unit volume
Explanation:
Bernoulli's equation states that pressure energy, kinetic energy, and potential energy per unit volume remain constant in ideal flow.
MCQs No. 59
When fluid flows through the narrow section of a horizontal pipe, its:
a. Pressure increases
b. Velocity decreases
c. Velocity increases and pressure decreases
d. Pressure and velocity both decrease
The Correct Answer is option c. Velocity increases and pressure decreases
Explanation:
According to Bernoulli's principle, an increase in speed causes a decrease in pressure.
MCQs No. 60
Which principle explains why roofs may be blown off during a strong windstorm?
a. Pascal's law
b. Archimedes' principle
c. Bernoulli's principle
d. Newton's first law
The Correct Answer is option c. Bernoulli's principle
Explanation:
Fast-moving air above the roof lowers the pressure, while the pressure inside the house remains higher, producing an upward force.
MCQs No. 61
A Venturi meter measures the:
a. Density of a liquid
b. Pressure of a gas
c. Rate of fluid flow
d. Temperature of a fluid
The Correct Answer is option c. Rate of fluid flow
Explanation:
A Venturi meter determines the flow rate by measuring the pressure difference between two sections of a pipe.
MCQs No. 62
The working of a filter pump is based on:
a. Hooke's law
b. Bernoulli's principle
c. Coulomb's law
d. Ohm's law
The Correct Answer is option b. Bernoulli's principle
Explanation:
Fast-flowing water creates low pressure that draws air from the attached vessel.
MCQs No. 63
A perfume sprayer works because:
a. Pressure increases with speed
b. High-speed air produces low pressure
c. Gravity pulls the liquid upward
d. Air becomes denser at high speed
The Correct Answer is option b. High-speed air produces low pressure
Explanation:
The pressure difference lifts the liquid through the tube and sprays it as fine droplets.
MCQs No. 64
Which force mainly opposes the motion of an object through a fluid?
a. Buoyant force
b. Electrostatic force
c. Drag force
d. Magnetic force
The Correct Answer is option c. Drag force
Explanation:
Drag force acts opposite to the direction of motion of an object moving through a fluid.
MCQs No. 65
At low speeds, drag force is directly proportional to:
a. Velocity²
b. Velocity
c. Radius³
d. Density²
The Correct Answer is option b. Velocity
Explanation:
For laminar flow, Stokes' law states that drag force is directly proportional to velocity.
MCQs No. 66
At very high speeds, drag force becomes approximately proportional to:
a. Velocity
b. Velocity²
c. Velocity³
d. Radius
The Correct Answer is option b. Velocity²
Explanation:
In turbulent flow, drag force varies approximately as the square of the speed.
MCQs No. 67
The coefficient of viscosity depends mainly upon the:
a. Shape of the container
b. Nature of the fluid
c. Colour of the liquid
d. Size of the vessel
The Correct Answer is option b. Nature of the fluid
Explanation:
Different fluids possess different intermolecular forces, resulting in different viscosities.
MCQs No. 68
Which liquid generally has a higher viscosity at room temperature?
a. Water
b. Petrol
c. Honey
d. Alcohol
The Correct Answer is option c. Honey
Explanation:
Honey flows much more slowly than water because it has a much higher viscosity.
MCQs No. 69
Which of the following is an example of a low-viscosity liquid?
a. Honey
b. Glycerin
c. Water
d. Tar
The Correct Answer is option c. Water
Explanation:
Water flows easily because its viscosity is much lower than that of honey or glycerin.
MCQs No. 70
The viscosity of gases generally ________ with increase in temperature.
a. Decreases
b. Increases
c. Remains zero
d. Becomes constant
The Correct Answer is option b. Increases
Explanation:
Unlike liquids, the viscosity of gases increases as temperature rises.
MCQs No. 71
Terminal velocity is achieved when:
a. Weight is greater than drag force
b. Drag force is greater than weight
c. Drag force equals the weight of the body
d. Gravity becomes zero
The Correct Answer is option c. Drag force equals the weight of the body
Explanation:
At terminal velocity, the upward drag force balances the downward weight, making the net force zero.
MCQs No. 72
Which of the following increases the terminal velocity of a falling sphere?
a. Increasing the viscosity of the liquid
b. Increasing the radius of the sphere
c. Decreasing the mass of the sphere
d. Increasing the density of the liquid only
The Correct Answer is option b. Increasing the radius of the sphere
Explanation:
According to Stokes' law, terminal velocity is directly proportional to the square of the sphere's radius.
MCQs No. 73
Rain drops fall with nearly constant speed after some time because they reach:
a. Escape velocity
b. Critical velocity
c. Terminal velocity
d. Orbital velocity
The Correct Answer is option c. Terminal velocity
Explanation:
Air resistance increases until it balances the weight of the rain drop, after which the speed remains constant.
MCQs No. 74
Which of the following is the best example of streamlining?
a. A cube-shaped car
b. An aircraft wing
c. A rectangular block moving through water
d. A flat metal plate moving edge-on
The Correct Answer is option b. An aircraft wing
Explanation:
Aircraft wings are designed with streamlined shapes to reduce drag and increase lift.
MCQs No. 75
Fluid dynamics mainly deals with the study of:
a. Solids at rest
b. Liquids and gases in motion
c. Thermal expansion of solids
d. Electric current in conductors
The Correct Answer is option b. Liquids and gases in motion
Explanation:
Fluid dynamics is the branch of physics that studies the motion of liquids and gases and the forces acting on them.
MCQs No. 76
Which instrument is commonly used to measure atmospheric pressure?
a. Hydrometer
b. Manometer
c. Barometer
d. Venturi meter
The Correct Answer is option c. Barometer
Explanation:
A barometer is used to measure atmospheric pressure and is based on the pressure exerted by the atmosphere on a column of mercury.
MCQs No. 77
A manometer is used to measure:
a. Atmospheric pressure only
b. Pressure difference between two points in a fluid
c. Fluid density
d. Volume flow rate
The Correct Answer is option b. Pressure difference between two points in a fluid
Explanation:
A manometer measures gauge pressure or the pressure difference between two points in a fluid system.
MCQs No. 78
Which of the following is an example of a compressible fluid?
a. Mercury
b. Water
c. Air
d. Oil
The Correct Answer is option c. Air
Explanation:
Gases such as air are compressible because their volume changes significantly under pressure.
MCQs No. 79
The continuity equation states that for an incompressible fluid:
a. Pressure remains constant everywhere.
b. Velocity remains constant everywhere.
c. The volume flow rate remains constant.
d. Density increases with velocity.
The Correct Answer is option c. The volume flow rate remains constant.
Explanation:
For steady incompressible flow, the volume of fluid passing through any cross-section per second remains constant.
MCQs No. 80
The total mechanical energy of an ideal fluid consists of:
a. Pressure energy only
b. Kinetic energy only
c. Potential energy only
d. Pressure, kinetic, and potential energies
The Correct Answer is option d. Pressure, kinetic, and potential energies
Explanation:
Bernoulli's equation expresses the conservation of pressure energy, kinetic energy, and gravitational potential energy.
MCQs No. 81
Which of the following is NOT a practical application of Bernoulli's principle?
a. Venturi meter
b. Perfume sprayer
c. Aircraft wing
d. Electric heater
The Correct Answer is option d. Electric heater
Explanation:
An electric heater works on electrical resistance, not on Bernoulli's principle.
MCQs No. 82
A fluid flowing through a horizontal pipe enters a narrow section. In that section, the fluid pressure:
a. Increases
b. Decreases
c. Remains unchanged
d. Becomes atmospheric
The Correct Answer is option b. Decreases
Explanation:
The fluid speeds up in the narrow section, causing its pressure to decrease according to Bernoulli's principle.
MCQs No. 83
Which force is mainly responsible for terminal velocity?
a. Magnetic force
b. Drag force
c. Electrostatic force
d. Nuclear force
The Correct Answer is option b. Drag force
Explanation:
As a body falls, drag force increases until it balances the weight, producing terminal velocity.
MCQs No. 84
Stokes' law is applicable to:
a. Very high-speed turbulent flow
b. Slow-moving spherical bodies in viscous fluids
c. Motion of planets
d. Compressible gases only
The Correct Answer is option b. Slow-moving spherical bodies in viscous fluids
Explanation:
Stokes' law applies to small spheres moving slowly through viscous fluids under laminar flow conditions.
MCQs No. 85
Which quantity opposes the motion of fluid layers?
a. Pressure
b. Surface tension
c. Viscosity
d. Buoyant force
The Correct Answer is option c. Viscosity
Explanation:
Viscosity is the internal friction that resists the relative motion between adjacent fluid layers.
MCQs No. 86
The SI unit of dynamic viscosity is also written as:
a. Pa·s
b. Pa/m
c. N/m
d. J·s
The Correct Answer is option a. Pa·s
Explanation:
The SI unit of dynamic viscosity is Pascal-second (Pa·s), which is equivalent to N·s m⁻².
MCQs No. 87
Which property of a fluid determines how easily it flows?
a. Density
b. Viscosity
c. Pressure
d. Volume
The Correct Answer is option b. Viscosity
Explanation:
A fluid with low viscosity flows more easily than a fluid with high viscosity.
MCQs No. 88
Which liquid flows most easily under ordinary conditions?
a. Honey
b. Glycerin
c. Water
d. Tar
The Correct Answer is option c. Water
Explanation:
Water has much lower viscosity than honey, glycerin, or tar, allowing it to flow more readily.
MCQs No. 89
The SI unit of pressure energy per unit volume is:
a. Joule
b. Pascal
c. Newton
d. Watt
The Correct Answer is option b. Pascal
Explanation:
Pressure energy per unit volume is simply pressure, whose SI unit is Pascal (Pa).
MCQs No. 90
Which theorem relates the speed of efflux of a liquid to the height of the liquid column?
a. Pascal's theorem
b. Bernoulli's theorem
c. Torricelli's theorem
d. Archimedes' principle
The Correct Answer is option c. Torricelli's theorem
Explanation:
Torricelli's theorem states that the speed of efflux is
MCQs No. 91
A streamlined shape helps to:
a. Increase drag force
b. Reduce drag force
c. Increase viscosity
d. Increase pressure
The Correct Answer is option b. Reduce drag force
Explanation:
Streamlining allows the fluid to flow smoothly around an object, reducing resistance.
MCQs No. 92
Which of the following is a dimensionless quantity?
a. Pressure
b. Density
c. Reynolds number
d. Viscosity
The Correct Answer is option c. Reynolds number
Explanation:
Reynolds number has no unit because it is the ratio of inertial force to viscous force.
MCQs No. 93
The resistance experienced by a body moving through air is called:
a. Buoyant force
b. Gravitational force
c. Drag force
d. Electrostatic force
The Correct Answer is option c. Drag force
Explanation:
Drag force always acts opposite to the direction of motion through a fluid.
MCQs No. 94
Which of the following has the highest viscosity?
a. Water
b. Alcohol
c. Honey
d. Petrol
The Correct Answer is option c. Honey
Explanation:
Honey is much more viscous than water, alcohol, or petrol, so it flows more slowly.
MCQs No. 95
When a body falls through a viscous liquid, the drag force acts:
a. Downward
b. Upward, opposite to the motion
c. Horizontally
d. Toward the centre of Earth only
The Correct Answer is option b. Upward, opposite to the motion
Explanation:
Drag force always acts opposite to the direction of motion, opposing the falling body.
MCQs No. 96
Which property of a fluid is responsible for internal friction?
a. Pressure
b. Density
c. Viscosity
d. Temperature
The Correct Answer is option c. Viscosity
Explanation:
Internal friction between adjacent fluid layers is due to viscosity.
MCQs No. 97
The pressure difference in a Venturi meter is produced because of:
a. Temperature change
b. Difference in fluid velocity
c. Magnetic field
d. Change in density only
The Correct Answer is option b. Difference in fluid velocity
Explanation:
The narrow section increases the fluid speed and lowers the pressure, creating a measurable pressure difference.
MCQs No. 98
Which of the following best describes an ideal fluid?
a. Compressible and viscous
b. Incompressible and non-viscous
c. Turbulent and compressible
d. Dense and viscous
The Correct Answer is option b. Incompressible and non-viscous
Explanation:
An ideal fluid is a hypothetical fluid with no viscosity and constant density.
MCQs No. 99
Which branch of physics studies the motion of liquids and gases?
a. Thermodynamics
b. Optics
c. Fluid Dynamics
d. Electrostatics
The Correct Answer is option c. Fluid Dynamics
Explanation:
Fluid dynamics deals with the motion of fluids and the forces that influence their movement.
MCQs No. 100
Which statement best summarizes Bernoulli's principle?
a. Pressure always increases with speed.
b. Faster-moving fluids have lower pressure.
c. Pressure is independent of velocity.
d. Fluid density always changes with speed.
The Correct Answer is option b. Faster-moving fluids have lower pressure.
Explanation:
Bernoulli's principle states that, in steady flow of an ideal fluid, an increase in fluid speed is accompanied by a decrease in pressure.
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