END; include ("common_short.php"); physics_header("",""); print <<Physics H133: Problem Set #\$ps_num Here are some hints, suggestions, and comments on the problem set.

## Two-Minute Problems

Remember to give a good explanation, no longer than two sentences.

1. Q14T.5: How would Eq.~(Q14.18) look like for proton emission? From which principle was this equation derived?
2. Q14T.6: Review p. 252.
3. Q15T.4: How are U and Pu bombs different in their explosion mechanism?

## Chapter Q14 and Q15 Problems

• Q14B.8: What is a Bq? See Eq. (Q14.25).
• Q15B.4: Adjust T so that the average thermal kinetic energy is enough to overcome the Coulomb barrier between the two deuterium nuclei.
• Q15B.6: To make a stable nucleus radioactive, one needs to change the N/Z ratio, add enough nucleons to make it unstable against alpha decay, or excite a nucleon to a higher energy level. Are these likely with electrons, alpha particles or gamma rays? Remember that weak interaction processes have a low probability of occuring and a gamma ray photon is absorbed only if the energy is just right and even then the excited level has to last long enough. Now consider neutrons.
• Q14S.2: Again, see Eq. (Q14.25).
• Q14S.7: Apply the ideas from Section Q14.1.
• Q15S.6: How much energy per hydrogen atom does solar fusion yield? How much energy has the sun radiated over its 5 billion year lifetime? Assume that the rate of energy production has remained constant over this period.
• Q15S.4: (a,b) Just plug in the given numbers into the scaling laws and evaluate the corresponding radius of devastation. (c) Interpret the numbers you obtained.

Physics H133: Hints for Problem Set \$ps_num.