What are four real world uses for sound?

Why is falling water considered an indirect for of solar energy? What is the 'Schroedinger's cat' thought experiment? What kind of matter can light transfer through? What name is given to material that will not allow electricity to pass through them? What material conducts electric current better than insulator but not as was as a conductor? What did netwon call the attraction between two objects such as the earth and an apple? Why is nuclear energy needed? How does the texture of a surface affect motion? How are nuclear energy and wind energy similar? What are the steps of how to focus a microscope? How long after the big bang did the first hydrogen nuclei form? Which term is used to indicate the process in which two small atomic nuclei emerge from a larger one? Who inveted the modern day ballpoint pen? What of the three states of matter do particles transfer significant amounts of heat energy by both conduction and convection? Who invented the cathode ray oscilloscope? Where do air masses collide? What do you cause when you squeeze the coils of a spring together? How can a car slowing down also be accelerating? If a boat is sinking because it has to much cargo How does density compare to the density of water? What is the difference between bidirectional energy meter and unidirectional energy meter?

What are four real world uses for sound?