Imagine that you take a metal spring, compress it to its most compact length, and tie some string around it to keep it compressed. There is now potential energy stored in the compressed spring. You then place the tied-up spring into a container of strong acid, and, after some time, the compressed spring completely dissolves (the string is not affected by the acid). What type of energy does the compressed spring have and what is it converted to when it dissolves in the acid?