Quiz12_16solutions

# Quiz12_16solutions - Quiz 12A Physics 221 Spring 2016...

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Quiz 12A Physics 221, Spring 2016 Section: Name: Problem 1. An o ffi cer in his parked cruiser spots a robber 10 meters away. When the police turn on the 400Hz siren, the robber notices the sound intensity is 0.026 W m 2 . If the o ffi cer is seated 1 meter from the siren, what is the intensity he perceives? I 1 = P A 1 and I 2 = P A 2 where A = 4 r 2 I 1 = 4 r 2 2 4 r 2 1 I 2 I 1 = 2 . 6 W m 2 How much energy does the siren emit after 10 seconds of operation? I = P A P = I 4 r 2 P 10 seconds = 326 Joules Problem 2. Determine the observed frequency the robber hears if he runs away at 2.0 m s 2 and the cruiser drives toward him at 10 m s 2 . (Speed of sound = 343 m s 2 ) F L = v + v L v - v s F S v L = - 2 and v S = 10 F L = 410 Hz

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Quiz 12B Physics 221, Spring 2016 Section: Name: Problem 1. An o ffi cer in his parked cruiser spots a robber 15 meters away. When the police turn on the 400Hz siren, the robber notices the sound intensity is 0.026 W m 2 . If the o ffi cer is seated 1 meter from the siren, what is the intensity he perceives?
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