Chapter 16: Problem 61
A person is playing a small flute 10.75 cm long, open at one end and closed at the other, near a taut string having a fundamental frequency of 600.0 Hz. If the speed of sound is 344.0 m/s, for which harmonics of the flute will the string resonate? In each case, which harmonic of the string is in resonance?
Short Answer
Step by step solution
Understanding the Problem
Formula for Harmonics in a Closed Pipe
Calculation of First Harmonic Frequency for Flute
Identifying Odd Harmonics for Flute
Matching Harmonics with String
Determining Resonating Harmonics
Conclusion
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Fundamental Frequency
Fundamental frequencies depend on the physical characteristics of the instrument, such as its size or shape. For example, in our exercise, the fundamental frequency of the string is given as 600 Hz. This is the base frequency from which other harmonics (integer multiples) are derived.
- The fundamental frequency is crucial because it determines the harmonics.
- Harmonics build on the fundamental frequency, creating a richer sound.
- Without knowing the fundamental frequency, we cannot accurately identify harmonics and their contributions to the sound.
Speed of Sound
Sound waves travel at different speeds depending on the medium. In air, at room temperature, the speed of sound is approximately 344 meters per second. This can vary with changes in temperature and other environmental factors but is constant for our calculations here.
- The speed of sound is critical when using formulas to calculate wavelengths and frequencies.
- Knowing this speed allows us to accurately find harmonics for instruments with pipes or strings.
- In the open-closed pipe system like the flute, the speed of sound helps determine the effective wavelength and frequency of the sound produced.
Open-Closed Pipe System
In such systems, only odd harmonics (such as the 1st, 3rd, 5th) are present. This is because the closed end must always have a node (point of no displacement), while the open end must have an antinode (point of maximum displacement).
- A pipe's physical length directly affects its resonant frequencies, determining how sound waves are reinforced.
- The relation between the wavelength \( \lambda \) and length \( L \) is given by \( \lambda_1 = 4L \) for the first harmonic.
- The resulting frequency for each harmonic is calculated based on its position as a multiple of this fundamental frequency.