1. The problem statement, all variables and given/known data A cylinder contains an ideal gas and rotates at angular speed w. Find the probability that a molecule is at radial position r from the axis of the cylinder. 2. Relevant equations Boltzmann distribution, P(E)∝Ω(E)exp(-E/kT) where Ω(E) describes the degeneracy of the energy level E. 3. The attempt at a solution E=mr2w2/2 with molecules having mass m. Ω(E)∝r because the area goes like 2πrl. Then P(E)∝rexp(-mr2w2/2kT). However apparently this is wrong and there should be no r present in the probability. I don't understand this - it's like for the Maxwell Bolztmann distribution the probability of having speed v has a degeneracy ∝v2. Also, apparently I should be using E=-mr2w2/2 - why is this? This is seen in 4.1 on page 1 here http://www.physics.ohio-state.edu/~jay/7602/Feb ho2.pdf Thanks for any help!