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Zorluk: ZorWave Properties and Mathematical Wave Equation

A progressive transverse wave traveling along a medium is described by the displacement equation y=0.05sin(160πt4πx)y = 0.05 \sin\left(160\pi t - 4\pi x\right), where xx and yy are in meters and tt is in seconds. What is the ratio of the maximum particle velocity to the wave propagation velocity? (Take π=3.142\pi = 3.142.)

Cevap: 0.628

Cevap

The ratio of the maximum particle velocity to the wave propagation velocity is 0.628.
For a progressive wave y=Asin(ωtkx)y = A \sin(\omega t - k x), the wave advances at speed v=ωk=160π4π=40 m/sv = \frac{\omega}{k} = \frac{160\pi}{4\pi} = 40\text{ m/s}. Meanwhile, individual particles vibrate transversely with simple harmonic motion where maximum velocity is vp,max=Aω=0.05×160π=8π m/sv_{p,\text{max}} = A\omega = 0.05 \times 160\pi = 8\pi\text{ m/s}. Taking the ratio gives vp,maxv=8π40=0.2π=0.2×3.142=0.6284\frac{v_{p,\text{max}}}{v} = \frac{8\pi}{40} = 0.2\pi = 0.2 \times 3.142 = 0.6284, which rounds to 0.628.

Adım Adım Çözüm

1
Extract parameters from the standard wave equation y=Asin(ωtkx)y = A \sin(\omega t - k x)
A=0.05 mA = 0.05\text{ m}, ω=160π rad/s\omega = 160\pi\text{ rad/s}, k=4π rad/mk = 4\pi\text{ rad/m}
Matching the given equation with standard progressive wave form yields the required wave constants.
2
Calculate the wave propagation velocity vv
v=ωk=160π4π=40 m/sv = \frac{\omega}{k} = \frac{160\pi}{4\pi} = 40\text{ m/s}
The speed at which the wave energy advances through the medium depends on angular frequency and wave number.
3
Calculate the maximum transverse particle velocity vp,maxv_{p,\text{max}}
vp,max=Aω=0.05×160π=8π m/s25.136 m/sv_{p,\text{max}} = A\omega = 0.05 \times 160\pi = 8\pi\text{ m/s} \approx 25.136\text{ m/s}
Particles perform simple harmonic motion, whose maximum speed is given by the product of amplitude and angular frequency.
4
Compute the ratio of maximum particle velocity to wave velocity
Ratio =vp,maxv=8π40=0.2π=0.2×3.142=0.6284= \frac{v_{p,\text{max}}}{v} = \frac{8\pi}{40} = 0.2\pi = 0.2 \times 3.142 = 0.6284
Dividing the maximum particle speed by the wave speed gives the desired dimensionless ratio.

Anahtar Kavram

Distinction between particle oscillation velocity and wave propagation velocity
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