$T{T_1}\left\{ \begin{array}{l} {p_o} = 1atm\\ {V_0} = 125c{m^3}.40 = 5000c{m^3} = 5l \end{array} \right. \to T{T_2}\left\{ \begin{array}{l} {p_1} = ?\\ {V_1} = 2,5l \end{array} \right.$
Áp dụng định luật $Boyle-Mariotte$ ta được:
${p_0}{V_0} = {p_1}{V_1} \to {p_1} = \dfrac{{{p_o}{V_o}}}{{{V_1}}} = \frac{{1.5}}{{2,5}} = 2atm$