It is given that :
Mass of bullet, [tex]m_{1}[/tex] = 0.05 Kg
Mass of block, [tex]m_{2}[/tex] = 10 kg
velocity after impact, v = 0.5 m/s
Let [tex]v_{1}[/tex] is the velocity with which the bullet is fired.
Using law of conservation of momentum :
[tex]m_{1}v_{1}+m_{2}v_{2} = (m_{1}+m_{2})v[/tex]
[tex]0.05 \times v_{1}+0=(0.05+10) \times 0.5\ (since, the block is at rest)[/tex]
[tex]0.05\times v=10.05\times 0.5[/tex]
[tex]m_{2}=100.5\ m/s[/tex]
