04        1.    Calculate the maximum possible efficiency of a heat engine operated using a hot source temperature of 700°C and a cold sink at
                    20°C.  Absolute zero is - 273°C.

e_max = (1 - T_C /T_H) x 100%

 T_H = 273 K + 700 K = 973 K

T_C = 273 K + 20 K = 293 K

e_max = (1 - 293 K / 973 K) x 100%

e_max = 69.9% _ANS

 

07        2.    Provide two alternative statements of the Second Law of Thermodynamics.

                    a.    Heat can flow spontaneously only from a hot source to a cold sink

                    b.    No heat engine can be constructed in which heat from a hot source can be converted entirely to work.

                    c.    The entropy of a closed system never decreases.

 

                            Any two of these three responses is acceptable.

 

Select the single best answer to the following multiple choice question.

 

04        3.    A heat engine 

                    a.         can violate the First Law of Thermodynamics.

                    b.         can violate the Second Law of Thermodynamics.

                    c.         produces work from a temperature difference.

                    d.         decreases entropy.