A steel piano string is attached, under tension, at each end to secure posts. When gently struck, a faint note can be detected coming from the string. The string is then cooled by blowing cold air over it and then is struck again. How does the note now detected compare to the previous one.

This is what i found on google “according to the collision theory, the following criteria must be met in order for a chemical reaction to occur: molecules must collide with sufficient energy, known as the activation energy, so that chemical bonds can break. molecules must collide with the proper orientation.” i hope this information you.