week14-3-tmp

week14-3-tmp - Time for the Class Evaluation and Final Exam...

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Time for the Class Evaluation and Final Exam Preparationi Please provide your input. The deadline is May 1 st , i.e. next Sunday. All students should have received an e-mail instruction. If you haven’t, please let me know. Please see course website for Information for final.
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Mass and Energy ܧ = ݉ × ܿ Mass and energy are related according to above equation. 1 C x 1 V = 1 J 1 e (i.e. unit charge) = 1.6x10 -19 C 1e x 1V = 1eV = 1.6x10 -19 J
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What is the energy released in this reaction? 2 He 4 + 4 Be 9 6 C 12 + 0 n 1 Reactants Be 9 9.012 186 u He 4 +4.002 603 u 13.014 789 u Products n 1.008 665 u C 12 +12.000 000 u 13.008 665 u Mass difference 13.014 789 u -13.008 665 u (0.006 124 u) x (1.66661 x 10 -27 kg/u) = 1.017 x 10 -29 kg Energy released E = mc 2 = (1.017 x 10 -29 kg) x (3.00 x 10 8 m/s 2 ) 2 = 9.15 x 10 -13 J (U: atomic weight)
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One element resulting from bombarding uranium with neutrons was barium. This was astonishing since barium has an atomic number much less than uranium. Lise Meitner and her nephew O. R. Frisch thought perhaps the uranium nucleus was splitting into two smaller nuclei, in a process called nuclear fission . 0 n 1 + 92 U 235 56 Ba 142 + 36 Kr 91 + 3 0 n 1 Each fission ~ 200 MeV = 3.2 × 10 ିଵଵ J
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Each of these fission reactions is initiated by a neutron, and each reaction emits several more neutrons. These neutrons can then initiate more fission reactions, etc. Chain Reactions. A chain reaction can thus release enormous quantities of energy. But achieving a chain reaction is difficult. Natural uranium is only 0.7% U-
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week14-3-tmp - Time for the Class Evaluation and Final Exam...

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