University Physics Al No 12 The Second Law of Thermodynamics Class Number ame I. Choose the Correct Answer 1. A real engine has an efficiency of 33%. The engine has a work output of 24J per cycle. How much heat energy is extracted from the high-temperature reservoir per cycle (D) (A)8J (C)48J D)72J E)The question can be answered only of the engine is a Carnot engine Solution Using the definition of the efficiency e-n we have 0-w24 72.7(J) 0.33 2. A real engine has an efficiency of 33%. The engine has a work output of 24J per cycle. For this T1=27 C. What can be concluded about Tp (C) A)TH=450°C.(B)TH=177°C(C)Tn>177°C(DTH<177°C.(E)177°C<TH<450°C Solution Since real heat engines have efficiencies less than a Carnot heat engine operating between the same two temperatures The efficiency of the Carnot engine is s=1-Is, so we have g=1-2>3 _27+273 =175 1-33%67% 3. Ten identical particles are to be divided up into two different containers. How many different configurations are possible? (B) (A)1 B)11 (C)120 (D)1024 (E)3628800 Solution: The possible configurations are configuration I|Ⅱ|Ⅲ|Ⅳ|VⅥⅦⅧxxI 4 5 6 7 10 10 6 3 4. Ten identical particles are to be divided up into two containers. Which configuration has the largest number of microstates? (D) (A)0,10 (B)3,7 (C)4,6 (D)5,5University Physics AI No. 12 The Second Law of Thermodynamics Class Number Name I．Choose the Correct Answer 1. A real engine has an efficiency of 33%. The engine has a work output of 24J per cycle. How much heat energy is extracted from the high- temperature reservoir per cycle? ( D ) (A) 8J (B) 16J (C) 48J (D) 72J (E) The question can be answered only of the engine is a Carnot engine. Solution: Using the definition of the efficiency QH W ε = , we have 72.7(J) 0.33 24 = = = ε W QH . 2. A real engine has an efficiency of 33%. The engine has a work output of 24J per cycle. For this engine TL=27°C. What can be concluded about TH? （ C ） (A) TH =450°C. (B) TH =177°C (C) TH >177°C (D) TH <177°C. (E) 177°C <TH <450°C. Solution: Since real heat engines have efficiencies less than a Carnot heat engine operating between the same two temperatures. The efficiency of the Carnot engine is H C T T ε =1− , so we have o 175 67% 27 273 1 33% 1 33% = + = − = − > ⇒ > C H H C T T T T ε 3. Ten identical particles are to be divided up into two different containers. How many different configurations are possible? （ B ） (A) 1 (B) 11 (C) 120 (D) 1024 (E) 3628800 Solution: The possible configurations are configuration I Ⅱ Ⅲ Ⅳ Ⅴ Ⅵ Ⅶ Ⅷ Ⅸ Ⅹ ⅩI N1 0 1 2 3 4 5 6 7 8 9 10 N2 10 9 8 7 6 5 4 3 2 1 0 4. Ten identical particles are to be divided up into two containers. Which configuration has the largest number of microstates? （ D ） (A) 0, 10 (B) 3, 7 (C) 4, 6 (D) 5, 5 Solution: