Question

A heat engine has an efficiency of 0.25 when it receives 250 J of heat. The amount of heat exhausted by the engine is A 190 B. 250 COJ D. 63) E None of the above. B During an isothermal process involving an ideal gas, 150 J of heat is removed from the system. The change in the internal energy of the gas is A 150J BOJ C 150J D. Unknown; not enough information is given to answer the question. E It violates physics laws.

Answer 1

[Answer A]: Given in formation is, efficiency of the heat engine Nu.E. = 0.25 amount of heat received by the heat engine Qs = 250 J (Joule) amount of heut exhausted (rejected) by the heat engine QR = ? According to Cernot's Theorem. Efficiency of the heat engine is given by, OR - NHE Qis where, Үне 0.25 as = 250 QR . substitute the values, QR ii 0.25 = 1- 250 = 1 - 0,25 0.75 .. ar 250 Qp 250 OR 0.75x250 QR = 187.5 I The amount of heat exhuusted by the heat engine is 187.5 J. No option matches with the answer. Option CE) is correct. [Answer B] : Heat removed from the system 150J The process is Isothermal, involving an ideal gus. Change in the internal energy of the gas AU= 9

The isothermal process is the one, there is no change in temperature. take place. Thut meuns, temperature during the isothermal process remainis constunt through-out. Also, the internul energy of an ideal is a function of temperature gus only. As, there is no change in the temperciture of an ideal gas during isothermal process, the internal energy do not change and remains constant. of the gus The change in internal energy AU=OJ Option (B) is correct.