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**Unformatted text preview: **following table, we display a list of all relative vibrational frequencies (12.158) that are < 6. Once the lowest frequency ω , 1 has been determined — either theoretically, numerically or experimentally — all the higher overtones ω m,n = ρ m,n ω , 1 are simply obtained by rescaling. Relative Vibrational Frequencies of a Circular Disk n backslashbigg m 1 2 3 4 5 6 7 8 9 . . . 1 1 . 000 1 . 593 2 . 136 2 . 653 3 . 155 3 . 647 4 . 132 4 . 610 5 . 084 5 . 553 . . . 2 2 . 295 2 . 917 3 . 500 4 . 059 4 . 601 5 . 131 5 . 651 . . . . . . . . . 3 3 . 598 4 . 230 4 . 832 5 . 412 5 . 977 . . . . . . 4 4 . 903 5 . 540 . . . . . . . . . . . . . . . . . . Nodal Curves When a membrane vibrates, its individual atoms move up and down in a quasi- periodic manner. As such, there is little correlation between their motion at different locations. However, if the membrane is set to vibrate in a pure eigenmode, say u n ( t, x, y ) = cos( ω n t ) v n ( x, y ) , (12 . 159) then all points move up and down at a common frequency ω n = radicalbig λ n , which is the square root of the eigenvalue corresponding to the eigenfunction v n ( x, y ). The exceptions are the points where the eigenfunction vanishes: v n ( x, y ) = 0 , (12 . 160) which remain stationary. The set of all points ( x, y ) ∈ Ω that satisfy (12.160) is known as the n th nodal set of the domain Ω. Scattering small particles (e.g., fine sand) over aof the domain Ω....

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