1) The beat frequency related to the interference between two waves is given by

where

is the beat frequency, and

and

are the frequencies of the two waves.
In our problem ,the beat frequency is

, and one of the two frequencies is

, so the frequency of the unknown tuning fork can be:


2) Given the previous problem, the frequency of the unknown tuning fork can be either 236 Hz or 244 Hz. When this unknown fork is struck with another fork of 250 Hz, the beat frequency is 6 Hz. Therefore, the only possibility is that the frequency of the first tuning fork is 244 Hz; in fact, we have:
