A cop cars siren has a frequency of 700Hz. If you are standing on the sidewalk as the cop car approaches you at the speed of 25 m/s, what frequency would you hear? The speed of sound is 340 m/s
https://www.easycalculation.com/formulas/doppler-shift-formula.html
To determine the frequency observed by the stationary observer, we need to consider the Doppler effect. The Doppler effect describes the change in frequency of a wave due to the relative motion between the source of the wave and the observer.
The observed frequency can be calculated using the following formula:
f' = (v + vo) / (v + vs) * f
where:
f' = observed frequency
f = source frequency (in this case, 700 Hz)
v = speed of sound (340 m/s)
vo = speed of observer (0 m/s, as the observer is stationary)
vs = speed of source (25 m/s, as the cop car is approaching the observer)
Plugging in the values into the formula, we get:
f' = (340 + 0) / (340 + 25) * 700
≈ (340 / 365) * 700
≈ 0.9315 * 700
≈ 651 Hz
Therefore, the frequency observed by the stationary observer would be approximately 651 Hz.