5. The answer to the previous question implies that there might be a relationship between the color index of a star and its main-sequence lifetime. What is that possible relationship

Waves are used in many practical applications to support work, entertainment, and health. one example is the use of ultrasound imaging to safely track the development of a growing fetus. what is a specific example of a practical application of waves in medicine, entertainment, safety, or other fields? provide a brief explanation of how the properties of waves are useful to that application.