45) An alpha particle (charge 2e) is aimed directly at a gold nucleus (charge 79e). What minimum initial kinetic energy must the alpha particle have to approach within 5.0 * 10-14 m of the center of the gold nucleus before reversing direction? Assume that the gold nucleus, which has about 50 times the mass of an alpha particle, remains at rest.

46) A beam of alpha particles is incident on a target of lead. A particular alpha particle comes in ?head-on? to a particular lead nucleus and stops 6.5??10^?14?m away from the center of the nucleus. (This point is well outside the nucleus.) Assume that the lead nucleus, which has 82 protons, remains at rest. The mass of the alpha particle is 6.64??10^?27?kg . Calculate the electrostatic potential energy at the instant that the alpha particle stops. Express your result in MeV.

47) A beam of alpha particles is incident on a target of lead. A particular alpha particle comes in ?head-on? to a particular lead nucleus and stops 6.5??10^?14?m away from the center of the nucleus. (This point is well outside the nucleus.) Assume that the lead nucleus, which has 82 protons, remains at rest. The mass of the alpha particle is 6.64??10^?27?kg What initial kinetic energy (in MeV) did the alpha particle have?

48) A triply ionized beryllium ion?Be³⁺, (a beryllium atom with three electrons removed), behaves very much like a hydrogen atom except that the nuclear charge is four times as great. (a) What is the ground-level energy of?Be³⁺?? How does this compare to the ground level energy of the hydrogen atom?

49) A triply ionized beryllium ion?Be³⁺, (a beryllium atom with three electrons removed), behaves very much like a hydrogen atom except that the nuclear charge is four times as great. What is the ionization energy of?Be³⁺?? How does this compare to the ionization energy of the hydrogen atom?