Answer these questions

11. Find the frequency of a sound wave moving in air at room temperature (20.0') with a wavelength of 0.667 m. 12. The human ear can detect sounds with frequencies between 20 Hz and 20 kHz. Find at 20.0' C. the largest and smallest wavelengths the ear can detect, assuming a speed of 343 m/s 13. If you clap your hands and hear the echo from a distant wall 0.20 s later, how far away is the wall? (assume 20.0 C). 14. What is the frequency of sound in air at 20.0' C having a wavelength of 0.382 m? 15. The speed of sound in sea water is about 1530 m/s. a. Is this faster or slower than sound in air? b. If a sound wave has a frequency of 250 Hz, what is its wavelength in sea water? 16. The lowest note in the classical repertoire is low D (f = 73.4 Hz), which occurs in an aria in Mozart's opera Die Entfuhrung aus dem Serail. If low D has a wavelength of 4.68 m, what is the speed of sound in air? 17. A tuning fork produces a sound with a frequency of 256 Hz and a wavelength in the air of 1.35 m. a. What value does this give for the speed of sound in air? b. What would be the wavelength of the wave produced by this tuning fork in water in which sound travels at 1530 m/s? 18. Animal behavior researchers hypothesize that elephants communicate by producing and detecting low-pitched sounds. a. What do we call these low sounds (if they are below our range of hearing)? b. One of the sound waves produced by an elephant has a frequency of 18 Hz. What is the wavelength of the sound wave? (assume v = 343 m/s)