As you stand near a railroad track, a train passes by at a speed of 33.7 m/s while sounding its horn at a frequency of 213 Hz. What frequency do you hear as the train approaches you? What frequency do you hear while it recedes? Use 343 m/s for the speed of sound in air. approaching: Hz receding: Hz Bats rely on sound localization to be able to fly during the night. On a cool 20C summer night, a bat produces an ultrasonic sound with a frequency of 37 kHz. The speed of sound in air at 20C is 340 m/s. What is the wavelength of this ultrasound, in meters? = While remaining stationary, the bat emits a sound pulse and receives an echo after 0.200 s. How far away, in meters, is the reflecting object from the bat? distance from the bat: A jet engine emits sound uniformly in all directions, radiating an acoustic power of 3.69 10 W. Find the intensity I of the sound at a distance of 40.5 m from the engine and calculate the corresponding sound intensity level . I = TOOLS x10 W/m B = = dB Macmillan Learning A weather emergency siren is mounted on a tower, 105 m above the ground. On one hand, it would be a good idea to make the siren very loud so that it will warn as many people as possible. On the other hand, safety regulations prohibit the siren from exceeding an intensity level of 106 dB for workers standing on the ground directly below the siren. Assuming that the sound is uniformly emitted, what is the maximum power that the siren can put out? maximium power output: How far away from the base of the tower can a person be and still be able to hear the siren? Neglect any absorption of sound energy by the air; although, in reality, such absorption would be significant at long distances. maximum audible distance: m W A crude approximation of voice production is to consider the breathing passages and mouth to be a resonating tube closed at one end. What is the fundamental frequency f if the tube is 0.260 m long, by taking air temperature to be 37.0C? f = Hz What would this frequency become if the person's breathing passage were filled with carbon dioxide instead of air? Assume the same temperature dependence for carbon dioxide as for air. f1,carbon dioxide = Question Credit: OpenStax College Physics Hz As you stand near a railroad track, a train passes by at a speed of 33.7 m/s while sounding its horn at a frequency of 213 Hz. What frequency do you hear as the train approaches you? What frequency do you hear while it recedes? Use 343 m/s for the speed of sound in air. approaching: Hz receding: TOOLS x10 Hz You are walking along a small country road one foggy morning and come to an intersection. While you are crossing, you hear an ambulance siren. As a paramedic, you know that the siren sounds at a frequency of 6.27 kHz. But, as an amateur musician with perfect pitch, you can tell that the frequency you are hearing is actually 6.9900 kHz. Is the ambulance moving toward or away from you? away toward At what speed is the ambulance traveling? speed: mph