Why are the ideas that earth undergoes change and is billionsof years old important for evolutionary theory?

Since the change makes sense because the age of the earth makes sense. I think If the Earth didn't change, evolution would happen much more slowly, if it happened at all. Change in the environments is a driving force for evolution; if the environment were static, then the same biological designs that worked today, would work tomorrow, and the day after that, and the day after that. Adaptation would reach a peak and then evolutionary progress would slow to a crawl. An old earth is important to evolutionary theory because evolution takes time. Significant evolutionary change generally only happens over many generations; in the case of some organisms, a generation can last decades.

The speed of  sound:   sound travels  at different speeds depending on what it istraveling through. of the three mediums (gas, liquid, and solid)  sound waves travel the slowest through  gases, faster  through  liquids, and fastest  through  solids.