1242_Physics ProblemsTechnical Physics

1242_Physics ProblemsTechnical Physics - Chapter 44 P44.42...

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Chapter 44 583 P44.42 (a) 400 400 10 370 10 100 10 148 12 10 3 . . . . pCi L Ci 1 L Bq 1 Ci L 1 m Bq m 3 3 = × F H G I K J × F H G I K J × F H G I K J = (b) N R R T == F H G I K J = F H G I K J F H G I K J λ 12 7 2 148 382 86 400 705 10 ln . . Bq m d ln2 s 1 d atoms m 33 ej (c) mass × F H G I K J F H G I K J 1 222 260 10 7 14 .. atoms m mol 6.02 10 atoms g 1 mol gm 3 23 3 Since air has a density of 120 . k 3 , the fraction consisting of radon is fraction = × 1200 217 10 14 17 . . 3 3 . *P44.43 (a) Let x , y denote the half-lives of the nuclei X, Y. R R Re e X Y t t xy X Y = −− 0 0 0685 2 1 1 104 .l n . h af a f bg , which gives 11 008260369 1 −= . h . (1) From the data: 77 2 . h. (2) Substitute (2) into (1): 77 2 1 xx =− . . h h. This reduces to the quadratic equation 2 77 2 934 6 0 −−= which has solutions: x = 87 84 . h or 10 64 h . Thus: xT = 87 84 3 66 , X h d a y s is the only physical root. From (2): yT 87 84 77 2 10 6 , ... Y h h . (b) From Table A.3, X is 224 Ra and Y is 212 Pb . (c) From Figure 44.18,
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