Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dynamics of a Massive Piston in an Ideal Gas: Oscillatory Motion and
  Approach to Equilibrium   We study numerically and theoretically (on a heuristic level) the time
evolution of a gas confined to a cube of size $L^3$ divided into two parts by a
piston with mass $M_L \sim L^2$ which can only move in the $x$-direction.
Starting with a uniform ``double-peaked'' (non Maxwellian) distribution of the
gas and a stationary piston, we find that (a) after an initial quiescent period
the system becomes unstable and the piston performs a damped oscillatory
motion, and (b) there is a thermalization of the system leading to a Maxwellian
distribution of the gas velocities. The time of the onset of the instability
appears to grow like $L \log L$ while the relaxation time to the Maxwellian
grows like $L^{7/2}$.

15
The categories of this paper are: nucl-ex
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The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
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The categories of this paper are: dg-ga
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ