1. The problem statement, all variables and given/known data A classical gas consists of N molecules; each molecule is composed of two atoms connected by a spring. Identify the dimensionality of the phase space that can be used to describe a microstate of the system. 3. The attempt at a solution I believe the answer is 12, but I'm not sure why. Since there are three cartesian coordinates (say x,y,z) and 3 corresponding conjugate momenta (px,py,pz). Thus the dimensionality is 6. But why would you multiply it by 2 to get 12? * Should I say 3N coordinates and 3N conjugate momenta?