Gas has to be above a certain temperature before it burns. The diagram shows two similar wire gauzes, one made of iron wire and one made of copper wire.
Each is held over a Bunsen burner. When the gas supply is turned on and ignited below the gauze.
How can these observ tions be explained?

firearm identification is the process of analyzing the bullets and cartridge cases left at a crime scene to determine if they came from a particular firearm. marks on the bullets and cartridges may be common to every firearm of that type. these are called class characteristics.

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y