A person hums into the top of a well and finds that standing waves are establish
ID: 777971 • Letter: A
Question
A person hums into the top of a well and finds that standing waves are established at frequencies of 42, 70, and 98 Hz. The frequency of 42 Hz is not necessarily the fundamental frequency. The speed of sound is 343 m/s. How deep is the well?A person hums into the top of a well and finds that standing waves are established at frequencies of 42, 70, and 98 Hz. The frequency of 42 Hz is not necessarily the fundamental frequency. The speed of sound is 343 m/s. How deep is the well?
A person hums into the top of a well and finds that standing waves are established at frequencies of 42, 70, and 98 Hz. The frequency of 42 Hz is not necessarily the fundamental frequency. The speed of sound is 343 m/s. How deep is the well?
Explanation / Answer
You notice that the difference between each of those frequencies is exactly 28Hz.
That means that 42-28 = 14 Hz is your fundamental frequency.
We know that
f = mv/2L, where
m = mth node
v = velocity
L = length
f = frequency
Thus,
L = mv/2f
L = (1)(343)/2(14)
L = 12.25 m