Answer:
8 Hz, 48 Hz
Step-by-step explanation:
The standing waves on a string (or inside a pipe, for instance) have different modes of vibrations, depending on how many segments of the string are vibrating.
The fundamental frequency of a standing wave is the frequency of the fundamental mode of vibration; then, the higher modes of vibration are called harmonics. The frequency of the n-th harmonic is given by
where
is the fundamental frequency
In this problem, we know that the wave's third harmonic has a frequency of
This means this is the frequency for n = 3. Therefore, we can find the fundamental frequency as:
Now we can also find the frequency of the 6-th harmonic using n = 6: