mechanical engineering MCQs – Page 160

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 Review each marked answer and report any item that may be outdated or unclear.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

3181. As the number of cylinders in multi-cylinder engine increases, the power to weight ratio_______________?
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A. Decreases upto a limit and then increases

B. Decreases

C. Remains same

D. Increases

3182. Scavenging is usually done to increase__________________?
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A. thermal efficiency

B. speed

C. fuel consumption

D. power output

E. all of the above

3183. The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed____________________?
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A. 80C

B. 320C

C. 180C

D. 240C

E. 120C

3184. An engine has a normal speed of 960 r.p.m. and no load speed of 1000 r.p.m. The speed droop of governor will be about___________________?
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A. 4%

B. 8%

C. 4%

D. 1%.

E. 2%

3185. A diesel engine as compared to petrol engine (both running ar rated load) is ____________________?
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A. equally efficient

B. less efficient

C. more efficient

D. other factors will decide it

E. unperdictable

3186. For same power and same speed, the flywheel of a four stroke engine as compared to two-stroke I.C. engine will be________________?
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A. unpredictable

B. dependent on other engine parameters

C. smaller

D. same size

E. bigger

3187. The reason for supercharging in any engine is to________________?
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A. none of the above

B. reduce weight and bulk for a given out-put

C. increase efficiency

D. increase power

E. effect fuel economy

3188. The knock in diesel engine occurs due to____________________?
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A. delayed burning of the first part of the charge

B. reduction of delay period

C. instantaneous and rapid burning of the first part of the charge

D. all ot the above

E. instantaneous atuo iginition of last part of charge

3189. Diesel fuel, compared to petrol is_________________?
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A. just about the same difficult to ignite

B. none of the above

C. less difficult to ignite

D. highly ignitable

E. more difficult to ignite

3190. The ratio of useful power; engine friction exhaust gas losses; cooling water, air and oil losses for a diesel engine is of the order of____________________?
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A. 40:30:15:15

B. 25:5:35:35

C. 25:35:5:35

D. 5:25:30:50

E. 25:5:10:60

3191. If the intake air temperature of I.C. engine increases, its efficiency will_________________?
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A. depend on other factors

B. unpredictable

C. remain same

D. decrease

E. increase

3192. Auto-ignition temperature is____________________?
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A. indicated by 50% distillation temperature

B. temperature at which it solidifies or congeals

C. that at which it catches fire without external aid

D. indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off

E. minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame

3193. A stoichiometric air-fuel ratio is______________________?
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A. lean mixture

B. chemically correct mixture

C. the ratio used at full rated parameters

D. rich mixture for idling

E. rich mixture for over loads

3194. In the opposed piston diesel engine, the combustion chamber is located________________?
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A. any when

B. between the pistons

C. there is no such criterion

D. above the piston (/;) below the piston

3195. Crankcase explosion in I.C. engines usuall occurs as ___________________?
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