Question 5 out of 10 points Determine the final pressure (kPa) for air undergoin

Question

Question 5 out of 10 points Determine the final pressure (kPa) for air undergoing a process from state 1 (T1-300 K, P1 -263 kPa) to a temperature of T2 1,157 Kif s2-s1 0.763 kl/kg-K. Assume variable specific heats (use the ideal gas tables) [None Given] 2,726.99 2.5% Selected Answer: Correct Answer: Question 6 out of 10 points Determine the change in specific entropy (k/kg-K) for Oxygen gas undergoing a process from state 1 (T1-300 K, P1 -102 kPa) to state 2 (T2 1,034 K, P2-994 kPa). Assume variable specific heats (use the ideal gas tables for Oxygen) Note: Give your answer to four decimal places Selected Answer: [None Given] Correct Answer: 0.6382 ± 2.5% Question 7 0 out of 10 points Determine the change in specific entropy (k/kg-K) for Nitrogen gas undergoing a process from state 1 (T1 300 K, P1 160 kPa) to state 2 (T2 1,160 K, P2 629 kPa). Assume variable specific heats (use the ideal gas tables for Nitrogen). Note: Give your answer to four decimal places. Selected Answer: [None Given] Correct Answer: 1.0653 2.5% Question 8 O out of 10 points Determine the final pressure (kPa) for a gas undergoing a process from state 1 (T1 357 K P1 277 kPa) to a temperature of T2 1,074 K ifs2-s1 0.763 k/kg-K. Assume constant specific heats as given below (DO NOT USE the ideal gas tables). Cp-1.135 k/kg-K Cy-0.759 kj/kg-K Selected Answer: [None Given] Correct Answer:1,011.81 1%

Explanation / Answer

5) T1 =300K T2=1157K

P1=263KPa P2=?

S2-S1=0.763KJ/Kg-K

Cp= 1.005 KJ/Kg-K Cv=0.718KJ/Kg-K R=0.287KJ/Kg-K

S2-S1 = Cpln(T2/T1) - R ln(P2/P1)

0.763 = 1.005 ln (1157/300) - 0.287 ln (P2/263)

P2 = 2080.31 KPa

6) T1 = 300K T2= 1034K

P1= 102 KPa P2= 994KPa

S2-S1 =?

Cp= 1.005 KJ/Kg-K Cv=0.718KJ/Kg-K R=0.287KJ/Kg-k

S2-S1 = Cpln(T2/T1) - R ln(P2/P1)

= 1.005 ln(1034/300) - 0.287 ln(994/102)

= 0.59016 KJ/Kg-K

S2-S1 = 0.59016 KJ/Kg-K

7) T1 = 300K T2= 1160K

P1=160KPa P2=629KPa

S2-S1 =?

Cp= 1.005 KJ/Kg-K Cv=0.718KJ/Kg-K R=0.287KJ/Kg-K

S2-S1 = Cpln(T2/T1) - R ln(P2/P1)

= 1.005 ln (1160/300) - 0.287 ln(629/160)

= 0.96628

S2-S1= 0.96628 KJ/Kg-K approx( 1.0662)

8) T1= 357K T2=1074K

P1=277KPa P2=?

S2-S1 = 0.736 KJ/Kg-K

Cp = 1.135 KJ/Kg-K Cv=0.759 KJ/Kg-K

R= Cp - Cv = 0.376 KJ/Kg-K

S2-S1 = Cpln(T2/T1) - R ln(P2/P1)

0.736 = 1.135 ln (1074/357) - 0.376 ln (P2/277)

P2 = 1011.809 KJ/Kg-K

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