mechanical engineering MCQs – Page 111

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 Review each marked answer and report any item that may be outdated or unclear.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

2201. 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______________?
0

A. Vi=V0B

B. U,<V0

C. Vri=Vm

D. Vt>V0

E. V,= U0

2202. For speed above 3000 km/hour, it is more advantageous to use____________________?
0

A. rockets

B. turbo-jet engine

C. hydraulic jet propulsion

D. propellers

E. ram-jet engine

2203. The ratio of specific weighf/h.p. of gas turbin and I.C engines may be typically of the order of_______________________?
0

A. 4:01

B. 2:01

C. 1:01

D. 1 : 6

E. 1:02

2204. Temperature of gases at end of compression as compared to exhaust gases in a gas turbine is_________________?
0

A. cant be compared

B. unpredictable

C. equal

D. higher

E. lower

2205. Losses in a centrifugal compressor are due to__________________?
0

A. diffuser losses

B. all of the above

C. inlet losses

D. none of the above

E. impeller channel losses

2206. Pick up the wrong statement ?
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A. axial flow compressors have instability region of operation

B. axial flow compressors are more stable than centrifugal type compressors but not as efficient

C. axial flow compressors have high capacity and efficiency

D. large gas turbines employ axial flow compressors

E. centrifugal compressors are used mainly on low flow pressure ratio gas turbines

2207. The hottest point in a gas turbine is______________________?
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A. uniformly heated

B. at the base

C. at the tip

D. between ~ to i of the blade height

E. in the center

2208. As the value of index is decreased, the volumetric efficiency will___________________?
0

A. may increase/decrease depending on compressor clearance

B. decrease

C. remain unaffected

D. increase

E. none of the above

2209. Water gas is produced by ___________________ ?
0

A. same way as the natural gas

B. partial combustion of caol, eke, anthractie coal or charcoal in a mixed air steam blast

C. passing steam over incandescent coke

D. carbonisation of coal

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

2210. A rocket engine for the combustion of its fuel_____________________?
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A. does not require oxygen

B. uses surrounding air

C. depends on electrical energy supplied by solar cells

D. carries its own oxygen

E. uses compressed atmospheric air

2211. The pressure ratio for an open cycle gas turbine compared to closed cycle gas turbine of same h.p. is_______________?
0

A. low/high depending on make and type

B. low

C. unpredictable

D. high

E. same

2212. For a two stage compressor* if index of compression for higher stage is greater than index of compression for lower stage, then the optimum pressure as compared to ideal case will___________________?
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A. increase

B. decrease

C. unpredictable

D. remain unaffected

E. other factors control it

2213. Actual compression curve is___________________?
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A. in between isothermal and adiabatic

B. better than isothermal and adiabatic

C. none of the above

D. same as adiabatic

E. same as isothermal

2214. In a compressor, free air delivered is the actual volume delivered at the stated pressure reduced to ____________________?
0

A. intake temperature and pressure conditions

B. N.T.P. conditions

C. none of the above

D. 20C and 1 kg/cm2

E. 0C and 1 kg/cm2

2215. Pick up the wrong statement about advantages of multistage compression____________________?
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A. mechanical balance is better

B. better lubrication is possible advantages of multistage

C. more loss of air due to leakage past the cylinder

D. more uniform torque, light cylinder and saving in work

E. air can be cooled perfectly in between

2216. Which of the following plants is smallest and lightest for genrating a given amount of power__________________?
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A. steam power plant

B. gas turbine plant

C. solar plant

D. diesel engine

E. petrol engine

2217. 1 m of air at atmospheric condition weighs approximately__________________?
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A. 0.5 kg

B. 1.0 kg

C. 2.2 kg

D. 1.3 kg

E. 3.2 kg

2218. The following property is most important for material used for gas turbine blade___________________?
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A. bulk modulus

B. toughness

C. fatigue

D. corrosion resistance

E. creep

2219. Propulsive efficiency is defined as ratio of___________________?
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A. thrust power and fuel energy

B. thrust power and propulsive power

C. propulsive power and fuel input

D. none of the above

E. engine output and propulsive power

2220. After-cooler is used to__________________?
0

A. increase pressure

B. decrease the delivery temperature for ease in handling

C. cool the air

D. cause moisture and oil vapour to drop out

E. reduce volume

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