On a Sunday afternoon you decide to go for a bike ride to your friends house. You travel east for 500 km and it takes you 15 minutes to get to your destination. Calculate the velocity.

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.

Can anybody me with this? ? (picture included.)

Explain earth's motion, using the terms "precession" and "rotation" in your answer.