Questions: Closed Pipes
Sound
A well acts as a closed pipe. When
wind blows across the top, it
creates a fundamental frequency of
30.6 Hz. How deep is the well?
(Speed of sound = 343 m/s)
(Unit = m)
Transcript text: Closed Pipes
Sound
A well acts as a closed pipe. When
wind blows across the top, it
creates a fundamental frequency of
30.6 Hz. How deep is the well?
(Speed of sound = 343 m/s)
(Unit = m)
Solution
Solution Steps
Step 1: Understanding the Problem
We need to determine the depth of a well that acts as a closed pipe, given the fundamental frequency and the speed of sound.
Step 2: Formula for Fundamental Frequency in a Closed Pipe
The fundamental frequency \( f \) of a closed pipe is given by:
\[ f = \frac{v}{4L} \]
where:
\( f \) is the fundamental frequency,
\( v \) is the speed of sound,
\( L \) is the length (or depth) of the well.
Step 3: Solving for the Depth of the Well
Rearrange the formula to solve for \( L \):
\[ L = \frac{v}{4f} \]
Step 4: Substituting the Given Values
Given:
\( f = 30.6 \) Hz,
\( v = 343 \) m/s,
Substitute these values into the formula:
\[ L = \frac{343 \, \text{m/s}}{4 \times 30.6 \, \text{Hz}} \]
Step 5: Calculating the Depth
Perform the calculation:
\[ L = \frac{343}{122.4} \approx 2.8021 \, \text{m} \]