Not sure how i am getting the direction wrong

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.

What do you think car designers do if the damage caused by a crash test is too severe?

The difference between a red shift and a blue shift has to do with wavelength frequency. t or f