Velocity in D'Alembert solution is the same as virtical velocity?

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    D'alembert Velocity
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SUMMARY

The discussion centers on the relationship between vertical velocity and wave propagation velocity in the context of the one-dimensional wave equation, specifically the D'Alembert solution. The equation presented is \(\frac{\partial^2 u}{\partial t^2} = c^2\frac{\partial^2 u}{\partial x^2}\), where \(c\) represents the vertical velocity of the vibrating string. The D'Alembert solution indicates that the vertical velocity of the vibrating string is equivalent to the wave's propagation velocity along the x-axis. However, it is noted that at different points along the string, the vertical velocities vary due to the differing distances traveled by points on the string during vibration.

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yungman
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One dimensional wave equation:

[tex]\frac{\partial^2 u}{\partial t^2} = c^2\frac{\partial^2 u}{\partial x^2}[/tex]

Where c is the vertical velocity of the vibrating string.



This will give D'Alembert solution of [tex]u(x,t) = \frac{1}{2}[f(x+ct) + G(x+ct)] + \frac{1}{2}[f(x+ct) + G(x+ct)][/tex]

Where [tex]u(x,t) = \frac{1}{2}[f(x+ct) + G(x+ct)][/tex] is the wave moving left with velocity c and [tex]\frac{1}{2}[f(x+ct) + G(x+ct)][/tex] is wave moving right with velocity c.


From the above, this mean the vertical velocity ( let's call u(x,t) axis ) of the vibrating string is the same as the propagating ( along x-axis ) velocity of the wave.

Question:

1) If the string is vibrating in the fundamental frequency ( single freq.). The velocity at different point is different because every point is vibrating at the same frequency and the point in the middle travel a farther distance than the points close to the end.

2) Is it really true the propagation velocity same as the vibrating velocity?
 
Last edited:
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Anyone have some insight?
 

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