Question

Julián approaches Alfredo in a straight line at a speed of 5m/sec, just when he is 100 meters away from Alfredo who is reposting, Julián emits a sound whose frequency is 250 Hz, what is the frequency that Alfredo perceives? How long does it take for the sound wave to reach Alfredo? (speed of sound 340 m/s) t= X/V

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A) 226.17 Hz, 0.294 sec

B) 238.28 Hz, 0.307 sec

C) 213.73 Hz, 0.279 sec

D) 205.21 Hz, 0.267 sec

Answer 1

The perceived frequency that Alfredo hears is 238.28 Hz and it takes 0.294 seconds for the sound wave to reach Alfredo.

Step-by-step explanation:

To solve this problem, we can use the formula for the Doppler effect. The formula for the perceived frequency of a sound wave depends on the relative velocity between the source and the observer. In this case, Julián is approaching Alfredo, so the relative velocity is the sum of Julián's velocity and the velocity of sound. The formula is given as:

f' = (v + vo) / (v + vs) * f

where f' is the perceived frequency, f is the original frequency, v is the velocity of sound, vo is the velocity of the observer, and vs is the velocity of the source. Plugging in the values, we get:

f' = (340 + 0) / (340 + 5) * 250 = 238.28 Hz

The time it takes for the sound wave to reach Alfredo can be calculated using the formula:

t = x / v

where t is the time, x is the distance, and v is the velocity of sound. Plugging in the values, we get:

t = 100 / 340 = 0.294 sec