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The predominant frequency of a certain fire truck’s siren is 1350Hz when at rest. What frequency do you detect if you move with a speed of 30.0 m /s (a) toward the fire truck, and (b) away from it?

Respuesta :

Answer:

(a) 1469.1 Hz

(b) 1230.9 Hz

Explanation:

Speed of source, Vs = 0

Speed of sound in air, V = 340 m/s

(a) Speed of observer, Vo = 30 m/s towards the source

Frequency, f = 1350 Hz

let the frequency is f' as observer moves towards the source

[tex]f' = \frac{V+V_{o}}{V}\times f[/tex]

[tex]f' = \frac{340+30}}{340}\1350[/tex]

f' = 1469.1 Hz

(b) Speed of observer, Vo = 30 m/s away from the source

Frequency, f = 1350 Hz

let the frequency is f' as observer moves away from the source

[tex]f' = \frac{V-V_{o}}{V}\times f[/tex]

[tex]f' = \frac{340-30}}{340}\1350[/tex]

f' = 1230.9 Hz

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