mechanical engineering MCQs – Page 4

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 Review each marked answer and report any item that may be outdated or unclear.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

61. The overall isothermal eiffciency of compressor is defined as the ratio of_______________?
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A. power to drive compressor to isothermal h.p.

B. work to compress air isothermally to work for actual compression

C. isothermal h.p. to the BHP of motor

D. isothermal h.p. to adiabatic h.p.

E. isothermal work to ideal work

62. Adiabatic compression is one in which___________________?
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A. entropy decreases

B. temperature during compression remains constant

C. temperature rise follows a linear relationship

D. work done is maximum

E. no heat leaves or enters the compressor cylinder during cornpression

63. For supplying intermittent small quantity of air at high pressure, following compressor is best suited__________________?
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A. centrifugal

B. axial

C. screw

D. turbo jet

E. reciprocating

64. To avoid moisture troubles, the branch connections from compressed air lines should be taken from_________________?
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A. left side of main

B. any location

C. right side of main

D. top side of main

E. bottom side of main

65. In a centrifugal pump casing, the flow of water leaving the_______________?
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A. radial

B. vortex

C. rectilinear

D. radial

E. centrifugal

66. In jet engines the products of combustion after passing through the gas lurbine are discharged into_______________?
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A. discharge nozzle

B. atmosphere

C. vacuum

D. back to the compressor

E. none of the above

67. A hydraulic intensifier normally consists of __________________?
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A. two cylinders, two rams and a storage device

B. special type of pump with storage device and a pressure regulator

C. a cylinder, a piston, storage tank and control valve

D. a cylinder and a ram

E. two co-axial rams and two cylinders

68. High specific speed of a pump implies it is_____________________?
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A. any one of the above

B. none of the above

C. axial flow pump

D. centrifugal pump

E. mixed flow pump

69. The following is true for an open cycle gas turbine having exhaust heat exchanger. Atmospheric air before entering the compressor is____________________?
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A. bled gas from turbine is heated and readmitted for complete expansion

B. heated

C. compressed air before entering the combustion chamber is heated

D. part of exhaust gases are heated and mixed up with atmospheric air to utilise exhaust heat

E. exhaust gases drive the compressor

70. Producer gas is produced by_____________________?
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A. partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast

B. same way as the natural gas

C. passing air and a large amount of steam over waste coal at about 65C

D. passing steam over incandescent coke

E. carbonisation of coal

71. Axial flow pump is started with its delivery valve________________?
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A. none of the above

B. kept 50% open

C. irrespective of any position

D. kept fully open

E. kept fully closed

72. A rocket works with maximum overall efficiency when air craft velocity is equal to the_________________?
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A. half the jet velocity

B. jet velocity

C. twice the jet velocity

D. average of the jet velocity

E. no such co-relationship with jet velocity exists

73. Hydraulic accumulator is used for____________________?
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A. generally high pressures to operate hydraulic machines

B. supplying large quantities of oil for very short duration

C. accumulating oil

D. supplying energy when main supply fails

E. accumulating hydraulic energy

74. Which of the following plants is smallest and lightest for genrating a given amount of power__________________?
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A. solar plant

B. steam power plant

C. gas turbine plant

D. diesel engine

E. petrol engine

75. The material commonly used for air craft gas turbine is__________________?
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A. stainless steel

B. high alloy steel

C. duralumin

D. titanium

E. Timken, Haste and Inconel allpys

76. According to fan laws, for fans having constant wheel diameter, the pressure varies________________?
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A. square of fan speed

B. square root of fan speed

C. cube of fan speed

D. none of the above

E. directly as fan speed

77. The ideal efficiency of simple gas turbine cycle depends on________________?
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A. none of the above

B. all of the above

C. minimum cycle temperature

D. pressure ratio

E. maximum cycle temperature

78. The compression ratio in a jet engine varies proportional to ____________________?
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A. speed

B. does not Vary

C. altitude

D. speed

E. Vspeed

79. Intercooling in gas turbine results in ____________________ ?
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A. increase in net output but decrease in thermal efficiency

B. increase in thermal efficiency but decrease in net output

C. increase in both thermal efficiency and net output

D. decrease in both thermal efficiency and net output

E. none of the above

80. Fast breeder reactor uses___________________?
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A. double circuit system of coolant cycle

B. boiler

C. single circuit system

D. multi pass system

E. direct cycle of coolant system

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