597_Physics ProblemsTechnical Physics

597_Physics ProblemsTechnical Physics - Chapter 20 P20.72...

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Chapter 20 599 P20.72 QQ cold hot =− or QQQ Al water calo + bg m cTT m c m c c fi w w c c w Al Al Al Al Al kg C kg 4186 J kg C kg 630 J kg C C J 7.86 kg C ±Jkg C −= + = ° + °−° = × ⋅° =⋅ ° di a f b g a f 0 200 39 3 0 400 0 040 0 3 70 629 10 800 3 .. . . . . *P20.73 (a) P == × × = × σ AeT 48 1 4 4 22 5 67 10 5 1 10 0 965 5 800 3 16 10 . . WmK m K W 24 2 ej af (b) T avg K K K =+= × 0 1 4 800 0 9 5 890 5 78 10 3 . This is cooler than 5 800 K by 5 800 5 781 5800 0327% = (c) × 5 67 10 0 1 5 1 10 0 965 4 800 81 4 4 . . m K 2 e j × = × 5 67 10 0 965 5 890 3 17 10 8 4 22 . W 0.9 5.1 10 W 14 This is larger than 3 158 10 22 . × W by 129 10 0408% 20 . . × × = W 3.16 10 W 22 . ANSWERS TO EVEN PROBLEMS P20.2 0105 . ° C P20.22 liquid lead at 805 ° C P20.4 87 0 . ° C P20.24 (a) 12 0 . M J; (b) + 12 0 J P20.6 The energy input to the water is 6.70 times larger than the laser output of 40.0 kJ. P20.26 −− nR T T 21 P20.28 (a) 567 J; (b) 167 J
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