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An organ pipe is open at both ends. It is producing sound at its third harmonic, the frequency of which is \(262 \mathrm{Hz}\). The speed of sound is \(343 \mathrm{m} / \mathrm{s} .\) What is the length of the pipe?

Short Answer

Expert verified
The length of the pipe is approximately 1.964 meters.

Step by step solution

01

Understand the Problem

We need to find the length of an organ pipe open at both ends, producing sound at its third harmonic. We know the frequency of the third harmonic is 262 Hz, and the speed of sound is 343 m/s.
02

Relationship in an Open Pipe

For a pipe open at both ends, harmonics are produced at frequencies given by \( f_n = n\frac{v}{2L} \), where \( v \) is the speed of sound, \( L \) is the length of the pipe, and \( n \) is the harmonic number. In this case, since we are dealing with the third harmonic, \( n = 3 \).
03

Solve for Length of Pipe using Third Harmonic Equation

Substitute the given values into the formula for the third harmonic: \( 262 = 3\frac{343}{2L} \). Rearrange to find \( L \):\[ L = \frac{3 \times 343}{2 \times 262} \]
04

Calculate the Length

Calculate the value of \( L \) using the formula from Step 3:\[ L = \frac{1029}{524} \approx 1.964 \text{ m} \]
05

Final Check

Verify the calculation by plugging the length back into the formula and checking if it gives the correct frequency for the third harmonic: \( 262 \approx 3\frac{343}{2 \times 1.964} \), which is approximately correct.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Harmonics
In the world of sound waves, harmonics are fundamental. They are the distinct frequencies at which sound resonates in musical instruments. For an organ pipe open at both ends, the harmonics are very special because they include all integer multiples of the fundamental frequency.

An open pipe supports harmonics at frequencies given by the formula:
  • \( f_n = n\frac{v}{2L} \)
Where:
  • \( f_n \) is the frequency of the nth harmonic,
  • \( n \) is the harmonic number (1 for the first harmonic, 2 for the second, and so on),
  • \( v \) is the speed of sound,
  • \( L \) is the length of the pipe.

For open pipes, harmonics are particularly rich and predictable. This is because the pipe supports standing waves at multiples of half wavelengths. These harmonics create overtones that enrich musical tones, contributing to the instrument's sound quality.
Speed of Sound
The speed of sound is a key factor in how we perceive and compute sound in various environments. At sea level and room temperature (around 20°C or 68°F), the speed of sound in air is approximately 343 meters per second (m/s). This value can vary slightly depending on factors such as air temperature, humidity, and pressure.

Why does this matter in organ pipes or other musical instruments? The speed of sound helps determine the frequency of sound waves, allowing us to calculate harmonics accurately. In our exercise, the speed of sound is essential in calculating the pipe length that results in a specific harmonic frequency. By knowing the speed at which sound travels through air, we can predict and tune musical notes, combining the physical properties of the pipe with the behavior of sound waves.
Frequency Calculation
Calculating frequency in an open pipe involves understanding how the speed of sound, harmonic number, and pipe length interplay. Using the formula \( f_n = n\frac{v}{2L} \), we can solve for any variable involved, whether it's frequency, pipe length, or speed of sound.

In this exercise, we know the frequency of the third harmonic (262 Hz) and the speed of sound (343 m/s). By substituting these values into the equation, we can isolate \( L \), the length of the pipe:
  • Rearrange the equation to solve for \( L \): \( L = \frac{n\cdot v}{2\cdot f_n} \)
  • Substitute the known values: \( L = \frac{3\cdot 343}{2\cdot 262} \)
  • This gives \( L \approx 1.964 \) meters.

This calculation showcases how interconnected these concepts are, allowing for precise control in creating musical sounds. Calculating the correct frequency ensures that each note played on an instrument is harmonious and pleasant to the ear.

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Most popular questions from this chapter

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