584_Physics ProblemsTechnical Physics

584_Physics ProblemsTechnical Physics - 586 Heat and the...

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586 Heat and the First Law of Thermodynamics Section 20.5 The First Law of Thermodynamics P20.28 (a) WP V =− × = + 0800 700 1013 10 10 567 53 .. . atm L Pa atm m L J 3 af a f ej e j (b) EQ W int J J J =+ = + = 400 567 167 P20.29 W int =+ QE W = −= int J J 500 220 720 The negative sign indicates that positive energy is transferred from the system by heat. P20.30 (a) QW = Area of triangle Q == 1 2 4 00 6 00 12 0 . m kPa kJ 3 (b) = − 12 0 . k J FIG. P20.30 P20.31 E int BC –0– W BC int since 0 bg CA –+– EW Q int and so <> < 00 0 , AB +–+ WE E B C A Q < →> 0 0 ,; ∆∆ int int since for so P20.32 V V BC B C B 3 atm 0.400 m kJ b g 300 00900 94 2 . W EE int int, C int, B Ci n t , B kJ kJ 100 94 2 579 . . int, Since T is constant, int, D int, C 0 V V DA
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