Acoustic transmission between air and water (a) consider an air-water interface for acoustic waves that are normally incident from the air side. what fraction of incident acoustic wave power is transmitted into the water? note that you can compute this by computing the fraction reflected, and the fraction transmitted is what is left over. (b) how about the opposite direction, from water to air? what fraction of normally incident power from the water side is transmitted into the air? (c) using your knowledge of anti-reflection coatings for electromagnetic waves, deter- mine the density, bulk modulus, and thickness of an acoustic anti-reflection coating that could be put on the air-water interface to eliminate reflections from the air side at a frequency of 400 hz. note that there is a range of possible solutions. (d) what kind of material would have these properties? a gas? a liquid? something in between? can you find any real material that comes close? note: if you think that you don't know a parameter that you need to know, then look it up.

You are about to open a container of soy milk but notice that there are instructions to “shake well before serving.” the soy milk is most likely a

19. explain why a magnet from your refrigerator could not be used to lift something as heavy as a car. (chapter 7 – pages 202-203) 20. can a magnet ever have a single pole? explain your answer. (chapter 7 – page 208) 21. what happens to the wavelength of a wave if the frequency is increased? (chapter 9 – pages 280-281) 22. an ocean wave has a wavelength of 10 m and a frequency of 4.0 hz. what is the velocity of the wave? show the appropriate equation from your book and show your work with units. (chapter 9 – page 282) 23. as you sit outside, the sound of a siren becomes lower in pitch. is the emergency vehicle moving away from or towards you? explain how you know. (chapter 10 – page 315-316) 24. why are two astronauts in space unable to hear one another? (chapter 10 – page 307) 25. explain in at least 3 sentences how electromagnetic waves form. (chapter 11 – page 338-339) 26. using the chart on page 345 in your textbook, what are the three types of electromagnetic wave with wavelengths shorter than those of visible light. give an example of each. (chapter 11 – pages 345-351) 27. explain why a leaf usually appears to be green, but a rose typically appears red. (chapter 12 – page 373) 28. what is the difference in light that is refracted compared to light that is reflected? think in terms of speed of light as well as what happens to light waves when they interact with a medium. (chapter 12 – pages 369-370) 29. how are concave and convex lenses different? (chapter 13 – page 408-410) 30. what type of mirror is used in rearview mirrors in cars? why is it important that these mirrors have the warning, “objects in mirror are closer than they appear.”? (chapter 13 – page 405)

If a stone with an original velocity of 0 is falling from a ledgeand takes 8 seconds to hoybthe ground whays the final velocity of the stone