1. What is the wavelength of a 340-Hz tone in air? What is the wavelength of a 34,000-Hz ultrasonic wave in air?
2. For years, marine scientists were mystified by sound waves detected by underwater microphones in the Pacific Ocean. These so-called T-waves were among the purest sounds in nature. Eventually they traced the source to underwater volcanoes, whose rising columns of bubbles resonated like organ pipes. What is the wavelength of a typical T-wave whose frequency is 7 Hz? (The speed of sound in seawater is 1530 m/s.)
3. An oceanic depth-sounding vessel surveys the ocean bottom with ultrasonic waves that travel 1530 m/s in sea-water. The time delay of the echo to the ocean floor and back is 6 s. Show that the depth of the water directly below the vessel is 4590 m.
4. A bat flying in a cave emits a sound and receives its echo 0.1 s later. Show that its distance from the cave wall is 19 m.
5. You watch distant Sally Homemaker driving nails into a front porch at a regular rate of 1 stroke per second. You hear the sound of the blows exactly synchronized with the blows you see. And then you hear one more blow after you see the hammering stop. Explain how you calculate that Sally is 340 m away from you.
6. Imagine a Rip van Winkle type who lives in the mountains. Just before going to sleep, he yells, "WAKE UP," and the sound echoes off the nearest mountain and returns 8 hours later. Show that the distance between Rip and the imaginary mountain is nearly 5000 km (about the distance from New York to San Francisco).
7. What beat frequencies are possible with tuning forks of frequencies 256, 259, and 261 Hz?
8. A grunting porpoise emits sound at 57 Hz. What is the wavelength of this sound in water, where the speed of sound is 1500 m/s?