3. (a) The range of audible frequencies of sound in air,assuming sufficient amplitude, is from about 20 Hz to 20, 000 Hz.What is the range of audible wavelengths? Take the speed of soundin still air to be v = 344m/s.
(b) Sound is detected when the eardrum is caused tovibrate. The diameter of the eardrum is about 10 mm. Suppose aperson whispers into your ear with an intensity, I = 10−8 W/m2 =E/(At), where E is the energy delivered to your eardrum, A is thearea of the eardrum, and t is the duration of the whisper. i. Whatis the decibel level of the whisper ? ii. Calculate the area of theeardrum. How much energy, E, is delivered to the eardrum during 1minute of the whisper ?
(c) A 1.5 metre long rope is stretched between twosupports with a tension that gives a speed of transverse waves of48 m/s. What is the wavelength and frequency of: i. the fundamentalfrequency? ii. the fourth harmonic?
(d) Two swift canaries fly towards each other, eachmoving at 15m/s relative to the ground, and each warbling a note offrequency 1,750Hz. i. What frequency does each canary hear from thenote of the other? ii. What wavelength will each canary measure forthe note of the other?
