by momentum conservation we can say
[tex]P_i = P_f[/tex]
since gun and bullet was initially at rest so initial momentum of both must be ZERO
[tex]0 = m_1v_{1f} + m_2v_{2f}[/tex]
[tex]0 = 3* 10^{-3}* 3000 + 1 * v_{2f}[/tex]
[tex]0 = 9 + v_{2f}[/tex]
[tex]v_{2f} = - 9 m/s[/tex]
so it will recoil back with speed 9 m/s
