Explanation:
The energy of the system before the collision must equal the energy after the collision.
After the collision the bullet and the block have a total mass of 18.41 kg and they move at a speed of 8.8 m/s. The kinetic energy after the collision is
[tex]\frac{18.41 kg (8.8 m/s)^2}{2} = 713 J[/tex]
Before the collision only the bullet has kinetic energy.
So we can now determine the speed of the bullet using
[tex]\frac{0.11kg (v^2)}{2} = 713 J\\v = 114 m/s[/tex]