Chapter 15, Problem 77A

To determine

To explain: If the two flute frequencies are getting closer or far apart.

Explanation of Solution

Introduction:

The beat frequency is the magnitude of difference between frequencies of two different waves.

Assume the frequency of the two flutes to be $f_1$ and $f_2$ respectively. The beat frequency is given by:

$f_{beat}=\left|f_1-f_2\right|$

Since the beat frequency is increasing, it implies that the difference between the two frequencies is also increasing. Hence, the two frequencies are getting far apart.

Conclusion:

Since the beat frequency is increasing, the two frequencies are getting far apart.