# Problem: Suppose an oncoming ambulance moving at 115 km/h emits a steady 785-Hz sound from its siren.What frequency, in Hz, is received by a person watching the oncoming ambulance? The speed of sound on this day is 345 m/s

###### FREE Expert Solution

Let the speed of the sound be vw

Speed of the source be vs

The frequency received by the person as the ambulance approaches is expressed as:

$\overline{){{\mathbf{f}}}_{{\mathbf{o}}}{\mathbf{=}}{\mathbf{f}}\mathbf{\left(}\frac{{\mathbf{v}}_{\mathbf{w}}}{{\mathbf{v}}_{\mathbf{w}}\mathbf{-}{\mathbf{v}}_{\mathbf{s}}}\mathbf{\right)}}$

Converting 115 km/h

###### Problem Details

Suppose an oncoming ambulance moving at 115 km/h emits a steady 785-Hz sound from its siren.

What frequency, in Hz, is received by a person watching the oncoming ambulance? The speed of sound on this day is 345 m/s