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Lecture 9 Nucleus - Forces

Lecture 9 Nucleus - Forces. ASTR 340 Fall 2006 Dennis Papadopoulos. FIRST IN CLASS EXAM ON THURSDAY OCT. 5 3.30-5.00 PM. BRING CALCULATOR. YOU CAN HAVE ONE PAGE OF NOTES EXAMS COVERS ALL LECTURES – GO OVER THE POWERPOINTS IN WEB, CHAPTERS 1- 4 AND CHAPTER 6 PAGES 165-173.

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Lecture 9 Nucleus - Forces

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  1. Lecture 9 Nucleus - Forces ASTR 340 Fall 2006 Dennis Papadopoulos

  2. FIRST IN CLASS EXAM ON THURSDAY OCT. 5 3.30-5.00 PM. BRING CALCULATOR. YOU CAN HAVE ONE PAGE OF NOTES EXAMS COVERS ALL LECTURES – GO OVER THE POWERPOINTS IN WEB, CHAPTERS 1- 4 AND CHAPTER 6 PAGES 165-173.

  3. Table 13-1, p.465

  4. Mass-Energy Equivalence PREVIEW E=mc2 EQUIVALENCE OF MASS AND ENERGY MASS+ENERGY CONSERVED MASS TRANSFORME INTO ENERGY AND ENERGY INTO MASS E=9x1016 (m/kg) Joules From Lecture 5 we found energy of a 1kg (e.g. steak) 4.5 MJ (1000 cal) In chemical reactions we get an efficiency of transforming mass into energy approximately 4.5x106/9x1016 =5x10-11 Chemical bond – Electromagnetic Force – e.g. NaCl In chemical reactions only the energy stored in outer electrons is released Nucleus does not play any role

  5. Covalent bond

  6. The Nuclear Force Nucleus involves only protons and neutrons (nucleons) Electrostatic repulsion of protons balanced by the nuclear force. Strong but short range – nearest neighbor. Fig. 13-3, p.468

  7. Fig. 13-4, p.469

  8. Binding Energy: A nucleus is dismantled by removing a nucleon at a time and the amount of work done in the process is measured. Next if we next reassemble the nucleons in the form of the original nucleus, an amount of energy equal to the work done would be released. This is the called the binding energy of the nucleus. It indicates how tightly bound is. Key quantity is the binding energy per nucleon. It is the binding energy divided by the number of nucleons. Curve of the binding energy

  9. Nuclear Binding Energy

  10. Fusion - Fission

  11. Fusion - Issues

  12. Fusion Cycles

  13. CNO Cycle

  14. Fission Fig. 13-12, p.478

  15. Chain Reaction

  16. DOUBLING TIMES Doubling time Growth factor 1 21=2 2 22=4 4 24=16 10 210=1024 25 3.3x107 50 1.1x1015 80 1.2x1024 Energy per U235 fission 235 MeV Critical Mass

  17. Fig. 14-6, p.514

  18. Table 13-3, p.483

  19. Energy per nucleon required to put together the nucleus of an element as a function of the mass number

  20. Fig. 13-14, p.481

  21. Radioactivity alpha decay Ra(226,88)->Rn(222,86)+He(4,2) U(238,92)->Th(234,90)+He(4,2) Beta decay C(14,6)->N(14,7)+e-+n

  22. Fig. 13-16, p.485

  23. Radioactive Dating U 238 ->Pb 206 determines when rocks were solidified 3.9 byears, meteorites 4.6 byears Fig. 13-15, p.482

  24. Fig. 14-10, p.516

  25. Fig. 14-14a, p.522

  26. Fig. 14-14b, p.522

  27. Fig. 14-15, p.523

  28. Fig. 14-16, p.524

  29. Fig. 14-17, p.525

  30. Fig. 14-18, p.526

  31. Fig. 14-26, p.537

  32. Fig. 14-27, p.538

  33. Fig. 14-5, p.512

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