Change in frequency as heard by an observer is given by the formula

$\overline{){{\mathbf{f}}}_{\mathbf{o}\mathbf{b}\mathbf{s}\mathbf{e}\mathbf{r}\mathbf{v}\mathbf{e}\mathbf{r}}{\mathbf{=}}{{\mathbf{f}}}_{\mathbf{s}\mathbf{o}\mathbf{u}\mathbf{r}\mathbf{c}\mathbf{e}}{\mathbf{\left(}}\frac{{\mathbf{v}}_{\mathbf{w}\mathbf{a}\mathbf{v}\mathbf{e}}\mathbf{\pm}{\mathbf{v}}_{\mathbf{o}\mathbf{b}\mathbf{s}\mathbf{e}\mathbf{r}\mathbf{v}\mathbf{e}\mathbf{r}}}{{\mathbf{v}}_{\mathbf{w}\mathbf{a}\mathbf{v}\mathbf{e}}\mathbf{\pm}{\mathbf{v}}_{\mathbf{s}\mathbf{o}\mathbf{u}\mathbf{r}\mathbf{c}\mathbf{e}}}{\mathbf{\right)}}}$

The wave and the observer move in the same direction so that the numerator becomes

(v_{wave} + v_{observer})

The observer and the source move in opposite directions. Thus the denominator becomes

(v_{wave} - v_{source})

For the first eagle (observer):

Two eagles fly directly toward one another, the first at 15.0 m/s and the second at 20 m/s. Both screech, the first one emitting a frequency of 3200 Hz and the second emitting a frequency of 3800 Hz. What frequencies do they receive if the speed of sound is 330 m/s?

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the The Doppler Effect concept. You can view video lessons to learn The Doppler Effect. Or if you need more The Doppler Effect practice, you can also practice The Doppler Effect practice problems.