3. The radius of a hydrogen nucleus is believed to be about 1.2 fm. (a) If an electron rotates around the nucleus at that radius, what would be its speed according to the planetary model? (b) What would be the total mechanical energy? (c) Are these values reasonable?

Calculate the equivalent energy of one atom of beryllium (9.0 amu) in joules, using the conversion factors of 1 amu = 931.5 MeV and 6.25 x 10¹8 eV = 1 joule.

3. A beam of helium-3 atoms (m = 3.016 u) is incident on a target of nitrogen-14 atoms (m = 14.003 u) at rest. Dur- ing the collision, a proton from the helium-3 nucleus passes to the nitrogen nucleus, so that following the col- lision there are two atoms: an atom of "heavy hydro- gen" (deuterium, m = 2.014 u) and an atom of oxygen-15 15.003 u). The incident helium atoms are moving at (m a velocity of 6.346 × 10° m/s. After the collision, the deu- terium atoms are observed to be moving forward (in the same direction as the initial helium atoms) with a velocity of 1.531 x 10' m/s. (a) What is the final velocity of the oxygen-15 atoms? (b) Compare the total kinetic energies before and after the collision.

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