05:23
University Physics with Modern Physics In SI Units
BIO Ultrasound and Infrasound.
(a) Whale communication. Blue whales apparently communicate with each other using sound of frequency $17 \mathrm{~Hz}$, which can be heard nearly $1000 \mathrm{~km}$ away in the ocean. What is the wavelength of such a sound in seawater, where the speed of sound is $1531 \mathrm{~m} / \mathrm{s} ?$ (b) Dolphin clicks. One type of sound that dolphins emit is a sharp click of wavelength $1.5 \mathrm{~cm}$ in the ocean. What is the frequency of such clicks? (c) Dog whistles. One brand of dog whistles claims a frequency of $25 \mathrm{kHz}$ for its product. What is the wavelength of this sound? (d) Bats. While bats emit a wide variety of sounds, one type emits pulses of sound having a frequency between $39 \mathrm{kHz}$ and $78 \mathrm{kHz}$. What is the range of wavelengths of this sound?
(e) Sonograms. Ultrasound is used to view the interior of the body, much as $\mathrm{x}$ rays are utilized. For sharp imagery, the wavelength of the sound should be around one-fourth (or less) the size of the objects to be viewed. Approximately what frequency of sound is needed to produce a clear image of a tumor that is $1.0 \mathrm{~mm}$ across if the speed of sound in the tissue is $1550 \mathrm{~m} / \mathrm{s} ?$