mechanical engineering MCQs – Page 151

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 Review each marked answer and report any item that may be outdated or unclear.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

3001. According to first law of thermodynamics__________________?
0

A. total energy of a system remains constant

B. total internal energy of a system during a process remains constant

C. entropy of a system remains constant

D. internal energy, enthalpy and entropy during a process remain constant

E. work done by a system is equal to heat transferred by the system

3002. For reversible adiabatic process, change in entropy is_________________?
0

A. negative.

B. zero

C. minimum

D. unpredictable

E. maximum

3003. Reversed joule cycle is called_________________?
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A. Dual cycle

B. Carnot cycle

C. Brayton cycle

D. Rankine cycle

E. Bell Coleman cycle

3004. The statement that molecular weights of all gases occupy the same volume is known as________________?
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A. Daltons law

B. Law of thermodynamics

C. Avogadros hypothesis

D. Joules law

E. Gas law

3005. Carnot cycle efficiency is maximum when______________?
0

A. initial temperature is 0K

B. final temperature is 0K

C. final temperature is 0C

D. initial temperature is minimum possible

E. difference between initial and final temperature is 0K

3006. The pressureof a gas in terms of its mean kinetic energy per unit volume E is equal to________________?
0

A. 3E/4

B. 2E/3

C. E/2

D. 5E/4

E. E/3

3007. Sensible heat is the heat required to __________________?
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A. change liquid into vapour

B. change vapour into liquid

C. convert saturated steam into dry steam

D. increase the temperature of a liquid of vapour

E. convert water into steam and superheat it

3008. Unit of thermal conductivity in M.K.S. units is ___________________?
0

A. kcal-m/hr C

B. kcal/hr m2 C

C. kcal-m/hr m2 C

D. kcal/kg m2 C

E. kcal-m/m2 C

3009. The insulation ability of an insulator with the presence of moisture would_________________?
0

A. none of the above

B. may increase/decrease depending on temperature and thickness of insulation

C. decrease

D. increase

E. remain unaffected

3010. Which of the following is a case of steady state heat transfer ___________________?
0

A. none of the above

B. all of the above

C. heating of building in winter

D. I.C. engine

E. air preheaters

3011. When heat is transferred form hot body to cold body, in a straight line, without affecting the intervening medium, it is referred as heat transfer by __________________?
0

A. convection

B. conduction and convection

C. conduction

D. radiation

E. convection and radiation

3012. Film coefficient is defined as Inside diameter of tube________________?
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A. Film coefficient x Inside diameter Thermalconductivity

B. Equivalent thickness of film

C. none of the above

D. Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity

E. Thermal conductivity Equivalent thickness of film Specific heat x Viscocity

3013. Temperature of steam at around 540C can be measured by ____________________?
0

A. thermocouple

B. thermometer

C. thermistor

D. thermopile

E. radiatiouv pyrometer

3014. A non-dimensional number generally associated with natural convection heat transfer is________________?
0

A. Reynold number

B. Prandtl number

C. Weber number

D. Nusselt number

E. Grashoff number

3015. Thermal diffusivity of a substance is ____________________?
0

A. proportional to (k)

B. inversely proportional to k

C. none of the above

D. inversely proportional to k2

E. proportional of thermal conductivity

3016. When heat is transferred from one particle of hot body to another by actual motion of the heated particles, it is referred to as heat transfer by ___________________?
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A. radiation

B. convection and radiation

C. conduction

D. conduction and convection

E. convection

3017. The rate of energy emission from unit surface area through unit solid angle, along a normal to the surface, is known as ________________?
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A. transmissivity

B. reflectivity

C. absorptivity

D. intensity of radiation

E. emissivity

3018. In heat exchangers, degree of approach is defined as the difference between temperatures of________________?
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A. cold water inlet and outlet

B. hot medium outlet and cold water outlet

C. hot medium inlet and outlet

D. hot medium outlet and cold water inlet

E. none of the above

3019. The ratio of heat flow Q1/Q2 from two walls of same thickness having their thermal conductivities as ATj 2K2 will be ________________?
0

A. 0.25

B. 0.5

C. 2

D. I

E. 4

3020. Emissivity of a white polished body in comparison to a black body is________________?
0

A. higher

B. depends upon the shape of body

C. same

D. lower

E. none of the above

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