研究所、轉學考(插大)◆普通物理學題庫下載題庫

9. The displacement of a string wave is given by: y(x,t) = y_msin(kx + ωt). The traveling wave velocity is:
(A) +2πkω
(B)-2πkω
(C) +kω  
(D) +ω/k  
(E) -ω/k  .