We can use the result from Part A to study a process of interest in atomic physics: a collision of two atoms that causes one of the atoms to ionize (lose an electron). In this case, is the energy needed to ionize one of the atoms, called the ionization energy. The most efficient way to ionize an atom in a collision with another atom is for the collision to be completely inelastic (atoms stick together after the collision). If the collision were perfectly elastic, then translational kinetic energy would be conserved, and there would be no energy left over for exciting the atom. If the collision were partially elastic, then some of the initial kinetic energy would be converted into internal energy, but not as much as in a perfectly inelastic collision. In practice, interatomic collisions are never perfectly inelastic, but analyzing this case can give a lower bound on the amount of kinetic energy needed for ionization.
Is it possible to ionize an atom of , initially at rest, by a collision with an atom of that has kinetic energy of 4.0 electron volts? The ionization energy of the cesium atom is 3.9 electron volts.
You can take the mass of the oxygen atom to be 16 atomic mass units and that of the cesium atom to be 133 atomic mass units. It doesn't matter what mass units you choose, as long as you are consistent. For this question, it is most convenient to use atomic mass units, since these are the numbers you are provided with.