task 7. Sound without smoke: a) Consider a sound wave with the frequency v = 1 kHz. which propagates in the medium of air. What is the amplitude of oscillation of a sound wave? What is the maximum speed of the oscillating air particles? i) at the threshold of hearing (0 dB) ii) at the pain threshold (130 dB) Compare your results with mean free wavelength 2 and thermal Velocity of the molecules at T = 300 K. b) Now consider two sound waves. These are given by the equations 1 = A cos (800t 2z) and 2 = A cos (630t 1,5z) What does the overlay look like? how big is hers Group velocity compared to the phase velocities of the two individual waves? = c) The first tone of the siren of a police car has the frequencyv = 390 Hz, the second v2 = 520 Hz i) At what speed the police car has to drive towards you so that you can both of them tones heard a whole step higher, ie at the frequencies 1.12246. V1 und 1.2246. V2 ii) At what speed did you approach the stationary police car. to the to hear the same tone shift? Windo Wechseln aktivieren