Why don't planets crash into each other?​

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.

Your town is considering building a biodiesel power plant describe at least two advantages and two disadvantages

How are positive ions different from neutral atoms