2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/40322We calculate the velocity of sound in an ideal gas of massive hadrons with non-vanishing baryon number. The gas is in thermal and chemical equilibrium. Also we show that the temperature dependence $T(τ) \cong T_{0} \cdot ({τ_{0} \over τ})^{c_{s}^{2}}$ is approximately valid, when the gas expands longitudinally according to the Bjorken law.LaTeX, 6 figures (included), 6 pages, changes are made in figure captions 1-5High Energy Physics - Phenomenologytext