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Zorluk: KolayResononace, Vibrating Strings, and Air Columns in Pipes

A stretched string of length 0.5 m0.5\text{ m} fixed at both ends vibrates in its fundamental mode. If the speed of transverse waves along the string is 200 m/s200\text{ m/s}, calculate the fundamental frequency of the string in hertz.

Cevap: 200 Hz

Cevap

The fundamental frequency of the vibrating string is 200 Hz200\text{ Hz}.
For a string fixed at both ends, the fundamental mode corresponds to a standing wave with half a wavelength spanning the length of the string (L=λ2L = \frac{\lambda}{2}, or λ=2L\lambda = 2L). Applying the wave relation v=fλv = f\lambda, the fundamental frequency is f=v2Lf = \frac{v}{2L}. Substituting v=200 m/sv = 200\text{ m/s} and L=0.5 mL = 0.5\text{ m} gives f=2002(0.5)=200 Hzf = \frac{200}{2(0.5)} = 200\text{ Hz}.

Adım Adım Çözüm

1
Identify the relationship between frequency, wave speed, and string length for the fundamental mode.
For a string fixed at both ends, the wavelength of the fundamental harmonic is λ=2L\lambda = 2L, giving the frequency formula f=v2Lf = \frac{v}{2L}.
The fundamental standing wave pattern contains nodes at both fixed ends and a single antinode at the center.
2
Substitute the given numerical values into the formula.
f=200 m/s2×0.5 m=2001=200 Hzf = \frac{200\text{ m/s}}{2 \times 0.5\text{ m}} = \frac{200}{1} = 200\text{ Hz}.
Dividing the wave speed by twice the length of the string yields the frequency in hertz.

Anahtar Kavram

Fundamental frequency of a vibrating string fixed at both ends
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