A train travelling at 14.77 m/s is approaching a stationary observer, and sounding a warning horn at 369.5 Hz. If the speed of sound is 324.1 m/s, calculate the frequency which the observer hears, in Hz with two digits of precision. →Vs Your Answer:

Pr5. Two identical loudspeakers are located at points (-10,0,0) and (0,0, 10) of our coor- dinate system, where the numbers in the brac- kets correspond to the (r, y, z) coordinates of the points, expressed in meters. The loudspeakers are driven by the same oscillator with a frequ- ency of 170 Hz. The speed of sound in air can be considered 340 m/s. a) Give the coordinates of those points loca- ted on the positive r axis where the sound waves coming from the two loudspeakers interfere con- structively. b) A receiver is started to move slowly from the origin (0,0,0) along a path lying in the r-y plane so that it receives constant sound intensity throughout its slow motion. What is the shape of the path the receiver should take?

One cue your hearing system uses to localize a sound (i.e., to tell where a sound is coming from) is the slight difference in the arrival times of the sound at your ears. Your ears are spaced approximately 20 cm apart. Consider a sound source 5.0 m from the center of your head along a line 45∘ to your right. What is the difference in arrival times? Give your answer in microseconds. Hint: You are looking for the difference between two numbers that are nearly the same. What does this near equality imply about the necessary precision during intermediate stages of the calculation?

A bat at rest sends out ultrasonic sound waves at 50.0 ? Hz and receives them returned from an object moving directly away from it at 28.5 ?/?. What is the received sound frequency?