mechanical engineering MCQs – Page 5

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 Review each marked answer and report any item that may be outdated or unclear.

mechanical engineering Mcqs

1. compressors gas turbines and jet engines 2. theory of machines 3. nuclear power plants 4. engineering materials 5. strength of materials mechanical engineering 6. thermodynamics 7. heat transfer 8. i c engines 9. steam boilers engines nozzles and turbines 10. engineering mechanics 11. fluid mechanics mechanical engineering 12. production technology 13. machine design 14. hydraulic machines 15. workshop technology 16. refrigeration and air conditioning

81. The thermodynamic efficiency of rotary compressor is based on_______________?
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A. isothermal compression

B. adiabatic compression

C. none of the above

D. polytropic compression

E. isentropic compression

82. Which is not identical for an atom and an isotope_________________?
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A. atomic number

B. position in periodic table

C. mass number

D. all of the above

E. chemical properties

83. The breeding gain in case of thermal breeder reactor as compared to fast breeder reactor is________________?
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A. higher/lower depending on the size of reactor

B. same

C. unity

D. higher

E. lower

84. The area of actual indicator diagram on an air compressor as compared to area of ideal indicator diagram is_____________________?
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A. unpredictable

B. more/less depending on compressor capacity

C. less

D. more

E. same

85. A centrifugal compressor works on the principle of__________________?
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A. generating pressure directly

B. centripetal action

C. conversion of pressure energy into kinetic energy

D. conversion of kinetic energy into pressure energy

E. combination of A. and D.

86. According to fan laws, for fans having constant wheel diameter, the air or gas capacity varies______________________?
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A. directly as fan speed

B. square of fan speed

C. cube of fan speed

D. square root of fan speed

E. none of the above

87. A closed gas turbine in which fuel is burnt directly in the air is not possible because of__________________?
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A. high specific volume

B. high friction losses

C. high pressure ratio

D. increasing gas temperature

E. paucity of 02

88. According to fan laws, at constant speed and capacity, the pressure and power vary_____________________?
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A. as square of density

B. inversely as square root of density

C. directly as the air or gas density

D. inversely as density

E. as square root of density

89. The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and turine and fixed higher and lower temperature) with increase in pressure ratio will___________________?
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A. increase first at fast rate and then slow

B. none of the above

C. decrease continuously

D. first increase, reach maximum and then decrease

E. increase first at slow rate and then fast

90. Reaction turbines are used for____________________?
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A. high head and high discharge

B. low head and high discharge

C. low head

D. high head and low discharge

E. high head

91. The ratio of outlet whirl velocity to blade velocity in case of centrifugal compressor is called__________________?
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A. velocity factor

B. blade effectiveness

C. velocity coefficient

D. slip factor

92. Temperature of gases at end of compression as compared to exhaust gases in a gas turbine is_________________?
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A. lower

B. higher

C. unpredictable

D. cant be compared

E. equal

93. Ram compression in turbojet involves____________________?
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A. increasing speed of incoming air

B. reduction of speed of incoming air and conversion of part of it into pressure energy

C. leakage losses

D. compression of inlet air

E. lost work

94. The effective power of gas turbines is increased by adding the following in compressor__________________?
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A. none of the above

B. nitrogen

C. ammonia and water vapour

D. carbon dioxide

E. hydrogen

95. Guide angle as per the aerofoil theory of Kaplan turbine blade design is defined as the angle between_________________?
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A. lift and resultant force

B. drag and resultant force

C. lift and tangential force

D. lift and drag

E. resultant force and tangential force

96. The operation of straightening a curved sheet metal, is known as____________________?
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A. coining

B. drawing

C. squeezing

D. planishing

97. A file removes the metal during___________________?
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A. both forward and return strokes

B. forward stroke

C. return stroke

D. none of these

98. Ferrite material is____________________?
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A. none of the above

B. the most fissionable material

C. basic raw material for nuclear plants

D. the basic fuel for nuclear paints

E. the material which absorbs neutrons and undergoes spontaneous changes leading to the formation of fissionable material

99. For speed above 3000 km/hour, it is more advantageous to use____________________?
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A. rockets

B. hydraulic jet propulsion

C. ram-jet engine

D. propellers

E. turbo-jet engine

100. If V, U and Vr represent the absolute velocity of fluid, velocity of blade, and relative velocity of fluid, and suffix i and o stand for entry and exit conditions, then in a rotary machine whose degree of reaction is unity______________?
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A. Vri=Vm

B. Vi=V0B

C. V,= U0

D. U,<V0

E. Vt>V0

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