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€ Chrome File Edit View History Bookmarks People Window Help JJ5521 WA Hwa 12 Chegg.com C https:/ ne 654271#Q3 /www.webassign t/web/Student/Assignment-Responses/Mast?dept Apps A&M; Organizations TCC Miscellaneous PT WTC S Sch onli 10. 2 points I Previous Answers OSColPhys1 5.1.005 My Notes Ask Your Teacher Suppose a woman does 500 J of work and dissipates 9400 J of heat in the process. (a) What is the decrease in her internal energy, assuming no change in temperature or consumption of food? (That is, there is no other energy transfer Express your answer in kcal. 2.366 kca (b) What is her efficiency? 1880 X Additional Materials Reading Submit Assignment Save Assignment Progress Home My Assignments Extension Request WebAssign 4.0 1997-2015 Advanced Instructional Systems, Inc. All rights reserved.Explanation / Answer
From first law of thermodynamics,
U = Q - W
= (-9400) - (500)
= -9900 J
1 kcal = 4184 J
U = ( -9900 J ) ( 1.0 kcal / 4184 J )
= - 2.366 kcal
Efficiency = work done / amount of energy used
= 500/9900
= 0.0505
Percentage of efficiency = 0.505*100 = 5.05 %
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