mechanical engineering MCQs – Page 38

Practise multiple-choice questions from mechanical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

1851. The saturation temperature of steam with increase in pressure increases____________________?
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A. linearly

B. slowly first and then rapidly

C. rapidly first and then slowly

D. inversely

E. none of the above

1852. The ratio of absolute viscosity to mass density is known as_________________?
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A. coefficient of viscosity

B. viscosity index

C. specific viscosity

D. coefficient of compressibility

E. kinematic viscosity
1853. Total pressure on a lmxlm gate immersed vertically at a depth of 2 m below the free water surface will be_______________?
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A. 1000 kg

B. 8000 kg

C. 2000 kg

D. 4000 kg

E. 16000 kg

1854. In accelerated circulation type boiler________________?
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A. water is fed under high pressure and high velocity

B. heating takes place at bottom and the water supplied at bottom gets converted into the mixture of stdam bubbles and hot water which rise to durm

C. feed pump is employed to supplement natural circulation in water wall type furnace

D. water is converted into steam in one pass without any recirculation

E. water is supplied in drum and through downcomers located in atmospheric conditon it passes to the water wall and rises to durm in the from of mixture of water and steam
1855. A body floats in stable equilibrium ____________________?
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A. metacentre has nothing to do with position of e.g. for determining stability

B. none of the above

C. when the metancentre is above e.g.

D. when its meatcentric height is zero

E. when its e.g. is below its center of buoyancy

1856. Working principle of dead weight pressure gauge tester is based on_______________?
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A. Daltons law of partial pressure

B. Newtons law of viscosity .

C. Pascals law

D. Avogadros hypothesis

E. Second law of thermodynamic

1857. The crown of the fire box is made hemispherical in order to___________________?
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A. withstand pressure inside boiler ,

B. give maximum strength

C. resist intense heat in fire box

D. enable easy,manufacture

E. give maximum space

1858. Which of the following substance will have same percentage in both proximate and ultimate analysis___________________?
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A. moisture

B. hydrogen

C. ash

D. volatile matter

E. none of the above

1859. Specific weight of sea water is more that of pure water because it contains_________________?
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A. suspended matter

B. all of the above

C. dissolved air

D. dissolved salt

E. heavy water

1860. The flow in which the particles of a fluid attain such velocities that vary from point to point in magnitude and direction as well as from instant to instant, is known as__________________?
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A. steady flow

B. streamline flow

C. uniform flow

D. one dimensional flow

E. turbulent flow
1861. The specific heat of superheated steam in kcal/kg is generally of the order of___________________?
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A. 0.8

B. 0.3

C. 0.1

D. 1

E. 0.5
1862. The flow in which each liquid particle has a definite path and their paths do not cross each other is called__________________?
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A. streamline flow

B. turbulent flow

C. one dimensional flow

D. uniform flow

E. steady flow

1863. The upper surface of a weir over which water flows is known is_____________________?
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A. crest

B. sill

C. contracta

D. weir top

E. nappe

1864. In forced recirculation type boiler__________________?
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A. heating of water takes place in stages

B. heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum

C. water is supplied in drum and through down-comers located in atmospheric condition it passes to the water wall and rises to drum in the form of mixture of water and steam

D. water is converted into steam in one pass without any recirculation

E. feed pump is employed to supplement natural circulation in water wall type furnace
1865. An odd shaped body weighing 7.5 kg and occupying 0.01 m3 volume will be completely submerged in a fluid having specific gravity of__________________?
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A. 1.25

B. 0.8

C. 1

D. 1.2

E. 0.75
1866. For water, at pressures below atmospheric___________________?
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A. melting point drops slightly and boiling point drops slightly

B. melting point rises slightly and boiling point drops markedly

C. none of the above

D. melting point rises markedly and boiling point drops markedly

E. melting point drops slightly and boiling point drops markedly

1867. In regenerative air preheater, the heat is transferred _____________________?
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A. none of the above

B. by direct mixing

C. from heating an intermediateanaterial and then heating the air from this material

D. from a metal wall from one medium to another

E. heat is transferred by bleeding some gas from furnace

1868. The two important forces for a floating body are__________________?
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A. gravity, pressure

B. inertial, gravity

C. buoyancy, gravity

D. buoyancy, inertial

E. buoyancy, pressure

1869. Mach number is significant in_____________________?
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A. none of the above

B. simultaneous motion through two fluids where there is a surface of dis-continuity, gravity force, and wave making effects, as with ships hulls

C. supersonics, as with projectiles and jet propulsion

D. all of fhe above

E. full immersion or completely enclosed flow, as with pipes, aircraft wings, nozzles etc.

1870. Alcohol is used in manometer, because____________________?
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A. it provides suitable meniscus for the inclined tube

B. it provides longer length for a given pressure difference

C. its density is less

D. it provides accurate readings

E. its vapour pressure is low
1871. At which pressure the properties of water and steam become identical_________________?
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A. 0.1 kg/cm2

B. 225.6 kg/cm2

C. 100 kg/cm2

D. it is never possible

E. 1 kg/cm2

1872. True one-dimensional flow occurs when_________________?
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A. the fluid particles move in plane or parallel planes and the streamline pat-terns are identical in each plane

B. the magnitude and direction of the velocity do not change from point to point in the fluid

C. the velocity of successive fluid par-ticles, at any point, is the same at suc-cessive periods of time

D. the direction and magnitude of the veiocity at all points are identical

E. velocity, depth, pressure etc. change from point to point in the fluid flow

1873. The bituminous coal is non-caking if its carbon content is_______________?
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A. 90-95%

B. 85-90%

C. 95-100%.

D. 81-85%

E. 78-81%
1874. The diameter of fire tube of Cornish boiler compared to its shell is__________________?
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A. one half

B. one third

C. two-fifth

D. three-fifth

E. one-fifth

1875. Proximate analysis of fuel is determination of percentage of ____________________?
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A. lower calorific value

B. rough analysis

C. fixed carbon, ash, volatile matter, moisture

D. higher calorific value

E. carbon, hydrogen, nitrogen, sulphur, moisture

1876. Duplex feed pumps are used in small steam boilers. These operate on the principle of_________________?
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A. reciprocating pump

B. centrifugal pump

C. ejector pump

D. gear pump

E. axial flow pump

1877. The pressure of reheat steam after passing through reheater compared to inlet condition is _________________?
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A. equal

B. may be more or less depending on capacity of reheater

C. less

D. more

E. none of the above

1878. The total energy of each particle at various places in the case of perfect incompres sible fluid flowing in continuous sream__________________?
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A. keeps on decreasing

B. unpredictable

C. remains constant

D. may increase/decrease

E. keeps on increasing

1879. The specific volume of steam with increase in pressure decreases_____________________?
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A. inversely

B. rapidly first and then slowly

C. slowly first and then rapidly

D. none of the above

E. linearly

1880. Mechanical equivalent of heat for 1 kcal or Joules equivalent is equal to_________________?
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A. 539 kgm

B. 421 kgm

C. 102 kgm

D. 421 kgm

E. 75 kgm

1881. The major axis of elliptical manholes on the shell should be provided___________________?
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A. longitudinally

B. circumferentially

C. anywhere

D. on dished end

E. vertically

1882. The difference between cornish boiler and lancashire boiler is that_________________?
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A. none/of the above

B. former is water tube type and latter is fire tube type

C. former is fire tube type and latter is water tube type boiler

D. former contains one fire tube and latter contains two fire tubes
1883. Primary air is the air used to__________________?
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A. convert CO (formed in lower zone of furnace) into C02 at higher zone

B. transport and dry the coal

C. air-delivered by forced draft fan

D. none ot the above

E. provide air around burners for obtaining optimum combustion

1884. Uniform flow occurs when_____________________?
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A. the direction and magnitude of the velocity at all points are identical

B. the magnitude and direction of the velocity do not change from point to point in the fluid

C. velocity, depth, pressure, etc. change from point to point in the fluid flow

D. the fluid particles move in plane or parallel planes and the streamline pat-terns are identical in each pleasure

E. the velocity of successive fluid paiticles, at any point, is the same at successive periods of time

1885. Which of the following instrument can be used for measuring speed of a submarine moving in deep sea__________________?
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A. Venturimeter

B. Orifice plate

C. hot wire anemometer

D. rotameter

E. pitot tube
1886. The change in internal energy in steam engines equals to__________________?
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A. none of the above

B. work done during compression.

C. change in enthalpy

D. work done during adiabatic expansion

E. work done during the rankine cycle ;
1887. Choose the wrong statement?
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A. Center of pressure acts at a greater depth than center of gravity

B. The horizontal component acts through the center of pressure for the vertical projection

C. The horizontal component of the hydro-static force on any surface is equal to the normal force on the vertical projection of the surface

D. he vertical component passes through the center of pressure of the volume

E. The vertical component of the hydrostatic force on any surface is equal to the weight of the volume of the liquid above the area

1888. Steady flow occurs when___________________?
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A. the direction and magnitude of the velocity at all points are identical

B. the fluid particles move in plane or parallel planes and the streamline pat-terns are identical in each plane

C. velocity, depth, pressure, etc. change from point to point in the fluid flow

D. the velocity of successive fluid particles, at any point, is the same at successive periods of time

E. the magnitude and direction of the velocity do not change from point to point in the fluid

1889. Fusible plug for boilers is made of fusible metal containing tin, lead, and___________________?
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A. aluminium

B. nickel

C. bismuth

D. copper

E. iron

1890. At the center line of a pipe flowing under pressure where the velocity gradient is zero, the shear stress will be_________________?
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A. maximum

B. negative value

C. zero

D. minimum

E. could be any value
1891. The diameter of tubes for natural circulation boiler as compared to controlled circulation boilers is___________________?
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A. could be more or less depending on other factors

B. more

C. same

D. less

E. none of the above

1892. The safety valve at superheater as compared to drum safety valve setting is set at___________________?
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A. any value

B. none of the above

C. higher value

D. same value

E. lower value
1893. In water wall furnace, the heat is transferred to the water-walls by _________________?
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A. radiation and conducton

B. convection

C. conduction

D. radiation and convection

E. radiation
1894. A safety valve in a locomotive starts leaking. The leaking medium will be_________________?
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A. water

B. wet steam

C. dry steam

D. supersaturated steam

E. super heated steam
1895. Bernoulli equation deals with the law of conservation of__________________?
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A. work

B. momentum

C. mass

D. force

E. energy
1896. Expanding steam to a very low pressure (high vacuum) in steam engines is _________________?
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A. uneconomical

B. essential

C. desirable

D. economical

E. optional

1897. The critical pressure at which latent heat of vaporisation is zero is________________?
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A. 1 kgf/cm2

B. 100 kgf/cm2

C. 225.65 kgf/cm2

D. 1 kgf/cm2

E. 273 kgf/cm2

1898. While steam expands in turbines, theoretically the entropy________________?
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A. none of the above

B. behaves unpredictably

C. decreases

D. increases

E. remains constant
1899. The flow in which conditions do not change with time at any point, is known as_________________?
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A. steady flow

B. one dimensional flow

C. streamline flow

D. uniform flow

E. turbulent flow

1900. Efficiency of rankine cycle can be increased by_________________?
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A. decreasing exhaust pressure

B. increasing number of regenerative heaters

C. decreasing initial steam pressure and temperature

D. increasing exhaust pressure

E. increasing the expansion ratio