ef152-rec-4-2

# ef152-rec-4-2 - as an echo. What is the frequency of the...

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EF 152 – Physics for Engineers Spring, 2009 Recitation 4.2 Sound: Beats, Doppler, Sonic Boom Task 1. Concept Questions 1. Observers A, B and C listen to a moving source of sound. The location of the wave fronts of the moving source with respect to the observers is shown at the right. Which of the following is true? a. frequency is highest at A b. frequency is highest at B c. frequency is highest at C d. frequency is the same at all three points 2. You are heading toward an island in a speedboat and you see your friend standing on the shore, at the base of a cliff. You sound the boat’s horn to alert your friend of your arrival. If the horn has a rest frequency of f 0 , what frequency does your friend hear? a. lower than f 0 b. equal to f 0 c. higher than f 0 3. In the previous question, the horn had a rest frequency of f 0 , and we found that your friend heard a higher frequency f 1 due to the Doppler shift. The sound from the boat hits the cliff behind your friend and returns to you
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Unformatted text preview: as an echo. What is the frequency of the echo that you hear? a. lower than f b. equal to f c. higher than f but lower than f 1 d. equal to f 1 e. higher than f 1 4. The traces below show beats that occur when two different pairs of waves interfere. For which case is the difference in frequency of the original waves greater? a. pair 1 b. pair 2 c. same for both pairs d. impossible to tell by just looking Task 2. Book Problems. 1. Chapter 15, Problem 19. 2. Chapter 15, Problem 52. Task 3: Police Car Siren Consider three cases in which the relative speed of a siren is 30 m/s with respect to you. For each case, determine the frequency that you hear. The siren emits a frequency of 300 Hz. A. You are at rest, and the siren is moving away at 30 m/s. B. Siren is at rest, and you are moving away at 30 m/s. C. Siren is in front of you and moving at a velocity of 45 m/s and you are moving at a velocity of 15 m/s. Pair 1 Pair 2...
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## This note was uploaded on 04/07/2009 for the course EF 152 taught by Professor Ab during the Spring '08 term at University of Tennessee.

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