ANSWER:
-12.9 m/s
STEP-BY-STEP EXPLANATION:
We have the following information:
[tex]\begin{gathered} m_r=3.27\text{ kg} \\ m_b=67.5\text{ g = 0.0675 kg} \\ V_{\text{fusil}1}=V_{\text{bala}1}=0 \\ V_{\text{bala}1}=625\text{ m/s} \end{gathered}[/tex]We can calculate the recoil velocity that would be the velocity of rifle 2, just like this:
[tex]m_r\cdot V_{\text{fusil}1}+m_b\cdot V_{\text{bala}1}=m_r\cdot V_{\text{fusil}2}+m_b\cdot V_{\text{bala}2}[/tex]Replacing and solving:
[tex]\begin{gathered} 3.27\cdot0+0.0675\cdot0=3.27\cdot V_{\text{fusil}2}+0.0675\cdot625 \\ 0=3.27V_{\text{fusil}2}+42.1875 \\ V_{\text{fusil}2}=-\frac{42.1875}{3.27} \\ V_{\text{fusil}2}=-12.9 \end{gathered}[/tex]The recoil velocity of the rifle is -12.9 m/s
