\[\begin{aligned}V_{\text{bơm}} &= S \cdot d = 8 \times 10^{-4} \cdot 0{,}25 = 2 \times 10^{-4} \, \text{m}^3 \\\Delta V &= 10 \cdot V_{\text{bơm}} = 10 \cdot 2 \times 10^{-4} = 2 \times 10^{-3} \, \text{m}^3 \\V_2 &= V_0 + \Delta V = 1{,}5 \times 10^{-3} + 2 \times 10^{-3} = 3{,}5 \times 10^{-3} \, \text{m}^3 \\p_2 &= p_0 \cdot \frac{V_0}{V_2} = 10^5 \cdot \frac{1{,}5 \times 10^{-3}}{3{,}5 \times 10^{-3}} = \boxed{42857 \, \text{Pa}}\end{aligned}\]