In an atomic physics experiment, two atoms collide with each other in such a way that the initial total momentum of the atoms is zero The atoms are chosen so that M2 =4.0 M1 In the collision, the atom Ml has a final velocity. V1f=-0.20 V1i. What is the ratio of the final kinetic energy to the initial kinetic energy of the system (the two atoms)? In other words, what is KEfinal / KEinitial in this collision?