What states of matter are present at the melting point

Liquid
Gas

Matter and substance are definitely related. All substances are matter but all matters are not substance. A matter can consist of numerous substances. Matter is generally a loose term used in respect to a substance. Any physical object can be casually called a matter. Matter and substance are sometimes used for the same context, but it is completely wrong. Numerous examples have already proved that a matter may or may not be a substance depending on its physical nature, but a substance is always a matter.

Elias is almost correct. he just got it backwards.the correct answer is that it demonstrates elastic potential energy transforming into kinetic energy.