The Physics
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Opus in profectus

Nucleosynthesis

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Problems

practice

  1. Hydrogen fusion in the sun is a multistep reaction, but the net result is that four hydrogen atoms fuse into one helium atom (plus a bunch of junk).

    11H → 42He + 2(0+1e + 00γ + 00ν)

    The mass of the sun is 1.99 × 1030 kg, 91% of which is hydrogen. Its power output is 3.85 × 1026 W. Determine…

    1. the mass of four hydrogen atoms
    2. the mass defect when four hydrogen atoms fuse into one helium atom (in atomic mass units and megaelectronvolts)
    3. the rate at which the sun's mass is decreasing
    4. the total mass destroyed if all the sun's hydrogen were converted into helium
    5. the expected lifetime of the sun (assuming its power output will remain constant)
  2. Write something.
  3. Write something.
  4. Write something.

conceptual

  1. Technetium is an artificially produced element that is used in nuclear medicine as a tracer. For each step in the process from production to use to eventual decay into a stable nucleus, write out the corresponding reaction in symbolic form.
    1. Molybdenum 98 (9842Mo) is bombarded with neutrons so that one sticks to the nucleus. This is known as neutron capture.
    2. The daughter nucleus of the previous reaction undergoes beta decay.
    3. The daughter nucleus of the previous reaction is metastable and undergoes gamma decay. (The gamma ray from this decay is detected and used to create an image of an affected tissue.)
    4. The daughter nucleus of the previous reaction undergoes beta decay to a stable nucleus.