mechanical engineering MCQs – Page 155

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 Review each marked answer and report any item that may be outdated or unclear.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

3081. According to Stefans law, the total radiation from a black body per second per unit area is proportional to____________________?
0

A. T2

B. l/T

C. absolute temperature

D. T5

E. t

3082. 40% of incident radiant energy on the surface of a thermally transparent body is reflected back. If the transmissivity of the body be 0.15, then the emissivity of surface is____________________?
0

A. 0.75

B. 0.45

C. 0.6

D. 0.4

E. 0.55

3083. A perfect black body is one which_______________?
0

A. transmits all heat radiations

B. abslprbs heat radiations of all wave lengths falling on it

C. fully opaque

D. reflects all heat

E. is black in colour

3084. In free con-vection heat transfer, Nusselt number is function of________________?
0

A. Grashoff no and Prandtl no.

B. none of the above

C. Prandtl no. and Reynold no

D. Grashoff no. and Reynold no

E. Grashoff no., Prandtl no and Reynold no

3085. The total emissivity power is .defined as the total amount of radiation emitted by a black body per unit_______________?
0

A. temperature

B. area and time

C. area

D. time

E. thickness

3086. The thermal diffusivities for gases are generally_____________________?
0

A. less than those for liquids

B. more than those for liquids

C. same as for the liquids

D. dependent on the viscosity

E. more than those for solids

3087. A grey body is one whose absorptivity _________________?
0

A. varies with the wave length of incident ray

B. there is no such criterion

C. varies with both

D. varies with temperature

E. does not vary with temperature and wave length of the incident ray

3088. The unit of Stefan Boltzmann constant is ____________________?
0

A. watt/cm4 K

B. watt2/cm K4

C. watt/cm2 K4

D. watt/cm2 K2

E. watt/cm2 K

3089. Depending on the radiating properties, a body will be black when_________________?
0

A. p = 0, x = 0 and a = 1

B. x = 0, a + p = 0

C. p= l,T = 0anda = 0

D. p = 0, x = 1 and a = 0

E. a = 0,x + p= 1.

F. re a = absorptivity, p == reflectivity, X = transmissivity

3090. Log mean temperature difference in case of counter flow compared to parallel flow will be________________?
0

A. less

B. same

C. more

D. depends on other factors

E. none of the above

3091. The thermal diffusivities for solids are generally__________________?
0

A. zerci

B. less than those for gases

C. more than those for liquids and gases

D. more or less same as for liquids and gases

E. jess than those for liquids

3092. Depending on the radiating properties, body will be transparent when________________?
0

A. a = 0,x + p= 1

B. p = 0, T= l,anda = 0

C. p = 0, x = 0 and a = 1

D. p=l,x = 0,anda = 0

E. X = 0, a + p = 1

3093. Joule sec is the unit of_________________?
0

A. universal gas constant

B. Plancks constant

C. none of the above

D. kinematic viscosity

E. thermal conductivity

3094. Absorptivity of a body will be equal to its emissivity___________________?
0

A. at all temperatures

B. at one particular temperature

C. at critical temperature

D. for a polished body

E. when system is under thermal equi-librium

3095. Plancks law holds good for________________?
0

A. all coloured bodies

B. polished bodies

C. none of the above

D. all of the above

E. black bodies

3096. The amount of radiation mainly depends on___________________?
0

A. none of the above

B. temperature of body

C. all of the above

D. type of surface of body

E. nature of body

3097. Thermal diffusivity of a substance is __________________?
0

A. inversely proportional to density of substance

B. inversely proportional to specific heat

C. directly proportional to thermal conductivity

D. all of the above

E. none of the above

3098. The energy distribution of an ideal reflector at higher temperatures is largely in the range of ___________________?
0

A. longer wavelength

B. wavelength has nothing to do with it

C. none of the above

D. shorter wavelength

E. remains same at all wavelengths

3099. The ignition coil in diesel engines produces voltage of the order of________________?
0

A. 20,000 volts

B. 6 to 12 volts

C. 80,000 volts

D. 240 volts

E. 1000 volts

3100. Method of governing used in petrol engine is________________?
0

A. combined governing

B. hit and miss governing

C. partial governing

D. quantity governing

E. quality governing

Previous Next

Showing 3081 to 3100 of 4266 mcqs