Engineering Thermodynamics - Practice Test

[#266] The air standard efficiency of an Otto cycle is given by (where r = Compression ratio and $$gamma $$ = Ratio of specific heats)

(A) $$1 - {{ ext{r}}^{gamma - 1}}$$

(B) $$1 + {{ ext{r}}^{gamma - 1}}$$

(C) $$1 - frac{1}{{{{ ext{r}}^{gamma - 1}}}}$$

(D) $$1 + frac{1}{{{{ ext{r}}^{gamma - 1}}}}$$

Correct Answer

(C) $$1 - frac{1}{{{{ ext{r}}^{gamma - 1}}}}$$

[#267] Work-done during adiabatic expansion is given by (where p 1 , v 1 , T 1 = Pressure, volume and temperature for the initial condition of gas, p 2 , v 2 , T 2 = Corresponding values for the final condition of gas, R = Gas constant and $$gamma $$ = Ratio of specific heats)

(A) $$frac{{{{ ext{p}}_1}{{ ext{v}}_1} - {{ ext{p}}_2}{{ ext{v}}_2}}}{{gamma - 1}}$$

(B) $$frac{{{ ext{mR}}left( {{{ ext{T}}_1} - {{ ext{T}}_2}} ight)}}{{gamma - 1}}$$

(C) $$frac{{{ ext{mR}}{{ ext{T}}_1}}}{{gamma - 1}}left( {1 - frac{{{{ ext{p}}_2}{{ ext{v}}_2}}}{{{{ ext{p}}_1}{{ ext{v}}_1}}}} ight)$$

(D) All of these

Correct Answer

(D) All of these

[#268] According to First law of thermodynamics,

(A) Total internal energy of a system during a process remains constant

(B) Total energy of a system remains constant

(C) Work-done by a system is equal to the heat transferred by the system

(D) Internal energy, enthalpy and entropy during a process remain constant

Correct Answer

(B) Total energy of a system remains constant

[#269] According to Kelvin-Planck’s statement of second law of thermodynamics,

(A) It is possible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

(B) It is impossible to construct a device which operates in a cyclic process and produces no effect other than the transfer of heat from a cold body to a hot body

(C) It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

(D) None of the above

Correct Answer

(C) It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

[#270] According to Kelvin-Planck's statement of second law of thermodynamics,

(A) It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

(B) It is possible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

(C) It is impossible to construct a device which operates in a cyclic process and produces no effect other than the transfer of heat from a cold body to a hot body

(D) None of the above

Correct Answer

(A) It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work

Engineering Thermodynamics - Study Mode

[#266] The air standard efficiency of an Otto cycle is given by (where r = Compression ratio and $$gamma $$ = Ratio of specific heats)

Correct Answer

[#267] Work-done during adiabatic expansion is given by (where p 1 , v 1 , T 1 = Pressure, volume and temperature for the initial condition of gas, p 2 , v 2 , T 2 = Corresponding values for the final condition of gas, R = Gas constant and $$gamma $$ = Ratio of specific heats)

Correct Answer

[#268] According to First law of thermodynamics,

Correct Answer

[#269] According to Kelvin-Planck’s statement of second law of thermodynamics,

Correct Answer

[#270] According to Kelvin-Planck's statement of second law of thermodynamics,

Correct Answer