Brock University
Physics 1P22/1P92
Winter 2015
Dr. D’Agostino
Tutorial 10 (Chapter 31: Nuclear Physics and Radioactivity)
Questions
Purpose: To understand nuclear structure and radioactivity.
1. How many electrons does a neutral
85 Rb
37
atom have? Explain.
2. Which nucleus is more dense, a lead nucleus or an iron nucleus? Explain.
3. Of the three nuclear decay process, α-decay, β-decay, and γ-decay, which result in a new
element? Explain.
4. Determine the daughter nucleus when a radioactive
5. Determine the daughter nucleus when a radioactive
6. Determine the daughter nucleus when a radioactive
210 Pb nucleus undergoes α-decay.
82
198 Au nucleus undergoes β − -decay.
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14 C nucleus undergoes γ-decay.
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7. After 10 days, one-quarter of a sample of radioactive nuclei remains undecayed. Determine
the half-life of the sample.
8. After 10 days, one-eighth of a sample of radioactive nuclei remains undecayed. Determine
the half-life of the sample.
9. After 10 days, one-sixteenth of a sample of radioactive nuclei remains undecayed. Determine
the half-life of the sample.
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Problems
Purpose: To understand nuclear structure and radioactivity.
1. Determine the approximate radius of a
2. Determine the binding energy of
7 Li,
3
64 Zn
30
nucleus.
which has an atomic mass of 7.016 003 u.
3. The binding energy of a nucleus is 225.0 MeV. Determine the mass defect of the nucleus in
atomic mass units.
4. (a) Energy is required to separate a nucleus into its constituent nucleons; this energy is the
total binding energy of the nucleus. In a similar way one can speak of the energy that
binds a single nucleon to the remainder of the nucleus. For example, separating 167 N into
15 N and a neutron takes energy equal to the binding energy of the neutron. Find the
7
energy (in MeV) that binds the neutron to the 167 N nucleus by considering the mass of
15 N (atomic mass = 15.000108 u) and the mass of 1 n (atomic mass = 1.008665 u), as
7
0
compared to the mass of 167 N (atomic mass = 16.006099 u).
(b) Similarly, one can speak of the energy that binds a single proton to the 167 N nucleus.
Following the procedure outlined in Part (a), determine the energy (in MeV) that binds
the proton (atomic mass = 1.007825 u) to the 167 N nucleus. The atomic mass of 156 C is
15.010599 u.
(c) Which nucleon is more tightly bound, the neutron or the proton?
5. After 17 days, 94.1% of a sample of radioactive nuclei remains undecayed. Determine the
half-life of the sample.
6. The isotope
32 P
15
has a half-life of 14.28 days. What is its decay constant in units of s−1 ?
7. The number of radioactive nuclei present at the start of an experiment is 3.84 × 1015 . The
number present twenty days later is 5.06 × 1014 . What is the half-life (in days) of this species
of radioactive nuclei?
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8. The half-life for the α-decay of 238
92 U is 4.47 × 10 yr. Determine the age (in years) of a rock
specimen that contains 60.0% of its original number of 238
92 U atoms.
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