A bullet is fired into a 12 kg block of wood. After the bullet stops in the block of wood the block has 29 J of kinetic energy. At what speed is the block moving?

The gun from the crime scene shows tool marks where the serial numbers are ground off. there are also tool marks on the bullets left behind. what information can the tool marks on the bullets and gun provide about the crime? what type of evidence does this information provide, individual or class?