How is velocity determined from a distance over time graph

Blank liquids and gases exert a buoyant force on objects placed in them

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?

Why do metals "give up" their valence electrons?