Speed of a moving observer toward stationary source (sound frequency)

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Homework Help Overview

The problem involves a stationary sound source emitting a frequency of 190 Hz and a moving observer (a car) that perceives a frequency of 198 Hz. The context is related to the Doppler effect in sound, where the speed of sound is given as 340 m/s.

Discussion Character

  • Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to apply the Doppler effect equation for a moving observer but expresses confusion about their calculations. Participants question the accuracy of the original poster's mathematical steps and suggest that the resulting velocity seems implausibly high.

Discussion Status

The discussion includes attempts to clarify the algebra involved in solving the equation. Some participants provide feedback on the calculations, indicating that there may have been errors in the original poster's approach. There is an acknowledgment of a corrected answer, but the overall consensus on the method remains unclear.

Contextual Notes

Participants are working within the constraints of the problem statement and the provided values, with some questioning the assumptions made in the calculations.

rechitzy
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Homework Statement



A stationary whistle emits a sound of 190 Hz. If a car hears the whistle with a frequency of 198 Hz, how fast was it moving (in m/s)? Use 340 m/s for the sound velocity

Homework Equations



f'=(1+Vo/V)f ======>>>> equation for the observer moving toward stationary source.

The Attempt at a Solution



f'=(1+Vo/V)f

198=(1+Vo/340)190

please help! what am i doing wrong?
 
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What did you get for your answer?
 
i got 353.3157
 
Well, then you made a mistake in your math. I believe your equation is right, but you seem to be messing up when solving the algebra. Your velocity should not be that fast.
 
ok i believe i did the 198/190 times 340 -1 is that right?
 
No, it's not.
 
ok i got a different answer now 14.3157 is this one right?
 

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