Original: Bohr, Mottelson and Rainwater were jointly awarded the 1975 Nobel Prize in Physics "for the discovery of the connection between collective motion and particle motion in atomic nuclei and the development of the theory of the structure of the atomic nucleus based on this connection".
Simplified: He won the Nobel Prize in 1975 for his works in physics: he discovered the connection of the collective motion and the single-motion particle in the atomic nucleus, and also for the development of the nuclear structure.