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A car horn emits a frequency of 400 hz. A car traveling at 20.0 m/s sounds the horn as it approaches a stationary pedestrian. What frequency does the pedestrian hear? The speed of sound in air is 343 m/s a) 425 hz b)450 c)375 d)400 e)200

Respuesta :

Answer:

[tex] f =425 \ Hz[/tex]

Explanation:

given,

Speed of sound = 343 m/s

speed of the car = 20 m/s

frequency of horn = 400 Hz

frequency of the sound pedestrian will hear = ?

using formula

         [tex]f = \dfrac{v}{v-v_s}f_0[/tex]

         [tex]f= \dfrac{343}{343 -20}(400)[/tex]

         [tex]f= \dfrac{343\times 400}{323}[/tex]

         [tex]f=1.062 \times 400[/tex]

         [tex] f =424.76[/tex]

        [tex] f =425 \ Hz[/tex]

The frequency of the sound pedestrian will hear is equal to [tex] f =425 \ Hz[/tex]

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