2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/130167Using molecular dynamics we study heat conduction and diffusion of hard disks in one dimensional narrow channels. When collisions preserve momentum the heat conduction $κ$ diverges with the number of disks $N$ as $κ\sim N^α$ $(α\approx 1/3)$. Such a behaviour is seen both when the ordering of disks is fixed ('pen-case' model), and when they can exchange their positions. Momentum conservation results also in sound-wave effects that enhance diffusive behaviour and on an intermediate time scale (that diverges in the thermodynamic limit) normal diffusion takes place even in the 'pen-case' model. When collisions do not preserve momentum, $κ$ remains finite and sound-wave effects are absent.4 pages, accepted in Phys.Rev.EStatistical Mechanicstext