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1080+ Fluid Mechanics (FM) Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Civil Engineering .

Chapters

Chapter: Fluid Properties and Flow Characteristics
201.

Choose the wrong statement

A. Fluids are capable of flowing
B. Fluids conform to the shape of the containing vessels
C. When in equilibrium, fluids cannot sustain tangential forces
D. When in equilibrium, fluids can sustain shear forces
Answer» D. When in equilibrium, fluids can sustain shear forces
202.

An orifice is said to be large, if

A. The size of orifice is large
B. The velocity of flow is large
C. The available head of liquid is more than 5 times the height of orifice
D. The available head of liquid is less than 5 times the height of orifice
Answer» D. The available head of liquid is less than 5 times the height of orifice
203.

A piece of metal of specific gravity 13.6 is placed in mercury of specific gravity 13.6, what fraction of it volume is under mercury?

A. The metal piece will simply float over the mercury
B. The metal piece will be immersed in mercury by half
C. Whole of the metal piece will be immersed with its top surface just at mercury level
D. Metal piece will sink to the bottom
Answer» C. Whole of the metal piece will be immersed with its top surface just at mercury level
204.

Dynamic viscosity of most of the liquids with rise in temperature

A. Increases
B. Decreases
C. Remain unaffected
D. Unpredictable
Answer» B. Decreases
205.

Select the correct statement

A. Local atmospheric pressure depends upon elevation of locality only
B. Standard atmospheric pressure is the mean local atmospheric pressure a* sea level
C. Local atmospheric pressure is always below standard atmospheric pressure
D. A barometer reads the difference between local and standard atmospheric pressure
Answer» B. Standard atmospheric pressure is the mean local atmospheric pressure a* sea level
206.

The flow in which the particles of a fluid attain such velocities that varies from point to point in magnitude and direction as well as from instant to instant, is known as

A. One dimensional flow
B. Uniform flow
C. Steady flow
D. Turbulent flow
Answer» D. Turbulent flow
207.

The specific weight of sea water is __________ that of pure water.

A. Same as
B. Less than
C. More than
D. None of these
Answer» C. More than
208.

Which of the following instruments is used to measure flow on the application of Bernoulli's theorem?

A. Venturimeter
B. Orifice plate
C. Nozzle
D. All of the above
Answer» D. All of the above
209.

An ideal flow of any fluid must satisfy

A. Pascal law
B. Newton's law of viscosity
C. Boundary layer theory
D. Continuity equation
Answer» D. Continuity equation
210.

The height of a water column equivalent to a pressure of 0.15 MPa is

A. 15.3 m
B. 25.3 m
C. 35.3 m
D. 45.3 m
Answer» A. 15.3 m
211.

The ratio of specific weight of a liquid to the specific weight of pure water at a standard temperature is called

A. Density of liquid
B. Specific gravity of liquid
C. Compressibility of liquid
D. Surface tension of liquid
Answer» B. Specific gravity of liquid
212.

A hydraulic press has a ram of 15 cm diameter and plunger of 1.5 cm. It is required to lift a weight of 1 tonne. The force required on plunger is equal to

A. 10 kg
B. 100 kg
C. 1000 kg
D. 1 kg
Answer» A. 10 kg
213.

The total head of a liquid particle in motion is equal to

A. Pressure head + kinetic head + potential head
B. Pressure head - (kinetic head + potential head)
C. Potential head - (pressure head + kinetic head)
D. Kinetic head - (pressure head + potential head)
Answer» A. Pressure head + kinetic head + potential head
214.

When the Venturimeter is inclined, then for a given flow it will show __________ reading.

A. Same
B. More
C. Less
D. None of these
Answer» A. Same
215.

Cavitation is caused by

A. High velocity
B. High pressure
C. Weak material
D. Low pressure
Answer» D. Low pressure
216.

An ideal flow of any fluid must fulfill the following

A. Newton's law of motion
B. Newton's law of viscosity
C. Pascal' law
D. Continuity equation
Answer» D. Continuity equation
217.

Surface tension

A. Acts in the plane of the interface normal to any line in the surface
B. Is also known as capillarity
C. Is a function of the curvature of the interface
D. Decreases with fall in temperature
Answer» A. Acts in the plane of the interface normal to any line in the surface
218.

Alcohol is used in manometers because

A. It has low vapour pressure
B. It is clearly visible
C. It has low surface tension
D. It can provide longer column due to low density
Answer» D. It can provide longer column due to low density
219.

The discharge through a wholly drowned orifice is given by (where H1 = Height of water (on the upstream side) above the top of the orifice, H2 = Height of water (on the downstream side) above the bottom of the orifice, and H = Difference between two water levels on either side of the orifice)

A. Q = Cd × bH₁ × √(2gh)
B. Q = Cd × bH2 × √(2gh)
C. Q = Cd × b (H2 - H1) × √(2gh)
D. Q = Cd × bH × √(2gh)
Answer» C. Q = Cd × b (H2 - H1) × √(2gh)
220.

If no resistance is encountered by displacement, such a substance is known as

A. Fluid
B. Water
C. Gas
D. Ideal fluid
Answer» D. Ideal fluid
221.

The kinematic viscosity is the

A. Ratio of absolute viscosity to the density of the liquid
B. Ratio of density of the liquid to the absolute viscosity
C. Product of absolute viscosity and density of the liquid
D. Product of absolute viscosity and mass of the liquid
Answer» A. Ratio of absolute viscosity to the density of the liquid
222.

Choose the correct relationship

A. Specific gravity = gravity × density
B. Dynamic viscosity = kinematic viscosity × density
C. Gravity = specific gravity × density
D. Kinematic viscosity = dynamic viscosity × density
Answer» B. Dynamic viscosity = kinematic viscosity × density
223.

The viscosity of water is __________ than that of mercury.

A. Higher
B. Lower
C. Same as
D. None of these
Answer» A. Higher
224.

Surface energy per unit area of a surface is numerically equal to

A. Atmospheric pressure
B. Surface tension
C. Force of adhesion
D. Force of cohesion
Answer» B. Surface tension
225.

Free surface of a liquid behaves like a sheet and tends to contract to smallest possible area due to the

A. Force of adhesion
B. Force of cohesion
C. Force of friction
D. Force of diffusion
Answer» B. Force of cohesion
226.

Which of the following statement is correct?

A. In a compressible flow, the volume of the flowing liquid changes during the flow
B. A flow, in which the volume of the flowing liquid does not change, is called incompressible flow
C. When the particles rotate about their own axes while flowing, the flow is said to be rotational flow
D. All of the above
Answer» D. All of the above
227.

Choose the wrong statement

A. Viscosity of a fluid is that property which determines the amount of its resistance to a shearing force
B. Viscosity is due primarily to interaction between fluid molecules
C. Viscosity of liquids decreases with increase in temperature
D. Viscosity of liquids is appreciably affected by change in pressure
Answer» D. Viscosity of liquids is appreciably affected by change in pressure
228.

The unit of dynamic viscosity in S.I. units is

A. N-m/s2
B. N-s/m2
C. Poise
D. Stoke
Answer» B. N-s/m2
229.

A perfect gas

A. Has constant viscosity
B. Has zero viscosity
C. Is in compressible
D. None of the above
Answer» D. None of the above
230.

In a static fluid

A. Resistance to shear stress is small
B. Fluid pressure is zero
C. Linear deformation is small
D. Only normal stresses can exist
Answer» D. Only normal stresses can exist
231.

One liter of water occupies a volume of

A. 100 cm3
B. 250 cm3
C. 500 cm3
D. 1000 cm3
Answer» D. 1000 cm3
232.

The maximum discharge over a broad crested weir is

A. 0.384 Cd × L × H1/2
B. 0.384 Cd × L × H3/2
C. 1.71 Cd × L × H1/2
D. 1.71 Cd × L × H3/2
Answer» D. 1.71 Cd × L × H3/2
233.

The ratio of absolute viscosity to mass density is known as

A. Specific viscosity
B. Viscosity index
C. Kinematic viscosity
D. Coefficient of viscosity
Answer» C. Kinematic viscosity
234.

Hot wire anemometer is used to measure

A. Pressure in gases
B. Liquid discharge
C. Pressure in liquids
D. Gas velocities
Answer» D. Gas velocities
235.

Venturimeter is used to

A. Measure the velocity of a flowing liquid
B. Measure the pressure of a flowing liquid
C. Measure the discharge of liquid flowing in a pipe
D. Measure the pressure difference of liquid flowing between two points in a pipe line
Answer» C. Measure the discharge of liquid flowing in a pipe
236.

The pressure measured with the help of a pressure gauge is called

A. Atmospheric pressure
B. Gauge pressure
C. Absolute pressure
D. Mean pressure
Answer» B. Gauge pressure
237.

In order to increase sensitivity of U-tube manometer, one leg is usually inclined by angle 'θ'. Sensitivity of inclined tube to sensitivity of U-tube is equal to

A. Sinθ
B. 1/Sinθ
C. Cos θ
D. 1/Cosθ
Answer» B. 1/Sinθ
238.

Capillary action is due to the

A. Surface tension
B. Cohesion of the liquid
C. Adhesion of the liquid molecules and the molecules on the surface of a solid
D. All of the above
Answer» D. All of the above
239.

The intensity of pressure on an immersed surface __________ with the increase in depth.

A. Does not change
B. Increases
C. Decreases
D. None of these
Answer» B. Increases
240.

Stoke is the unit of

A. Kinematic viscosity in C. G. S. units
B. Kinematic viscosity in M. K. S. units
C. Dynamic viscosity in M. K. S. units
D. Dynamic viscosity in S. I. units
Answer» A. Kinematic viscosity in C. G. S. units
241.

The vapour pressure over the concave surface is

A. Less man the vapour pressure over the plane surface
B. Equal to the vapour pressure over the plane surface
C. Greater than the vapour pressure over the plane surface
D. Zero
Answer» A. Less man the vapour pressure over the plane surface
242.

Mercury is often used in barometer because

A. It is the best liquid
B. The height of barometer will be less
C. Its vapour pressure is so low that it may be neglected
D. Both (B) and (C)
Answer» D. Both (B) and (C)
243.

Gradually varied flow is

A. Steady uniform
B. Non-steady non-uniform
C. Non-steady uniform
D. Steady non-uniform
Answer» D. Steady non-uniform
244.

The viscosity of water at 20°C is

A. One stoke
B. One centistoke
C. One poise
D. One centipoise
Answer» D. One centipoise
245.

According to Bernoulli's equation for steady ideal fluid flow

A. Principle of conservation of mass holds
B. Velocity and pressure are inversely proportional
C. Total energy is constant throughout
D. The energy is constant along a streamline but may vary across streamlines
Answer» D. The energy is constant along a streamline but may vary across streamlines
246.

Bernoulli equation deals with the law of conservation of

A. Mass
B. Momentum
C. Energy
D. Work
Answer» C. Energy
247.

If the surface of liquid is convex, men

A. Cohesion pressure is negligible
B. Cohesion pressure is decreased
C. Cohesion pressure is increased
D. There is no cohesion pressure
Answer» C. Cohesion pressure is increased
248.

The atmospheric pressure with rise in altitude decreases

A. Linearly
B. First slowly and then steeply
C. First steeply and then gradually
D. Unpredictable
Answer» B. First slowly and then steeply
249.

Dynamic viscosity of most of the gases with rise in temperature

A. Increases
B. Decreases
C. Remain unaffected
D. Unpredictable
Answer» A. Increases
250.

According to Bernoulli's equation

A. Z + p/w + v²/2g = constant
B. Z + p/w - v²/2g = constant
C. Z - p/w + v²/2g = constant
D. Z - p/w - v²/2g = constant
Answer» A. Z + p/w + v²/2g = constant

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